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Water Quality_ Principles and Practices of Water Supply Operations, Volume 4-American Water Works Association (2010)
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AdvocacyCommunicationsConferencesEducation and TrainingScience and TechnologySections
The Authoritative Resource on Safe Water®
Fourth Edition
Principles and Practices of Water Supply Operations
Water Quality
1P-4E-7.5C-1958-6/10-SB
WSO: W
ater Quality
AWWA is the authoritative resource for knowledge, information, and advocacy to improve the quality and supply of water in North America and beyond. AWWA is the largest organization of water professionals in the world, advancing public health, safety, and welfare by uniting the efforts of the full spectrum of the water community. Through our collective strength, we become better stewards of water for the greatest good of people and the environment.
A clear understanding of water quality is the basis for all water treatment processes. Water operators
need to recognize, monitor, and test for a wide variety of water quality elements and contaminants. They also must comprehend the regulations regarding safe water. This book is the premier reference on water quality for water treatment operators everywhere.
Completely revised and updated, Water Quality, Fourth Edition covers
Public water supply regulations, including potential •future rules Water quality monitoring and sampling, laboratory •certification, record keeping; and sample preservation, storage, and transportation Laboratory equipment and instruments •Microbiological contaminants •
Physical and aggregate properties of water •Inorganic chemicals, particularly chlorine residuals and disinfection by-products; •Organic and radiological contaminants, including health effects •Customer inquiries and complaint investigation •
Water Quality is Part Four of the five-part Principles and Practices of Water Supply Operations (WSO) series of training texts for water operators, developed and published by the American Water Works Association.
Additional titles in the Water Supply Operations SeriesWater Sources•Water Treatment•Water Transmission and Distribution•Basic Science Concepts and Applications•
1958 Water Quality Cover.indd 1 5/25/2010 3:35:37 PM
Water Quality
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PRINCIPLES AND PRACTICES OF WATER SUPPLY OPERATIONS SERIES
Water Sources, Fourth Edition
Water Treatment, Fourth Edition
Water Transmission and Distribution, Fourth Edition
Water Quality, Fourth Edition
Basic Science Concepts and Applications, Fourth Edition
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Water Quality
Fourth Edition
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6666 West Quincy AvenueDenver, CO 80235-3098303.794.7711www.awwa.org
Copyright © 1979, 1995, 2003, 2010 American Water Works Association.All rights reserved.Printed in the United States of America.
No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopy, recording, or any information or retrieval system, except in the form of brief excerpts or quotations for review purposes, without the written permission of the publisher.
Project Manager/Senior Technical Editor: Melissa ValentineTechnical Editor: Linda BevardCover Design: Cheryl ArmstrongProduction: Kayci Wyatt, TIPS Technical Publishing, Inc.
DisclaimerMany of the photographs and illustrative drawings that appear in this book have been furnished through the courtesy of various product distributors and manufacturers. Any mention of trade names, commercial products, or services does not constitute endorsement or recommendation for use by the American Water Works Association or the US Environmental Protection Agency. In no event will AWWA be liable for direct, indirect, special, incidental, or consequential damages arising out of the use of information presented in this book. In particular, AWWA will not be responsible for any costs, including, but not limited to, those incurred as a result of lost revenue. In no event shall AWWA’s liability exceed the amount paid for the purchase of this book.
Library of Congress Cataloging-in-Publication Data
Ritter, Joseph A. Water quality / by Joseph A. Ritter.—4th ed. p. cm. — (Principles and practices of water supply operations) Rev. ed. of: Water quality. 2003. Includes bibliographical references and index. ISBN 978-1-58321-780-1 1. Water quality. 2. Water quality—Measurement. I. American Water Works Association. II.Water quality. III. Title.
TD370.W392 2010 628.1'61—dc22 2010004522
ISBN 10: 1-58321-780-0ISBN 13: 978-1-58321-780-1
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v
Contents
Foreword ................................................................................................................ viiAcknowledgments .................................................................................................... ixIntroduction ............................................................................................................. xi
Chapter 1 Public Water Supply Regulations ............................................... 1Safe Drinking Water Act ........................................................... 1Current and Future Rules Affecting Drinking Water Systems.... 23Drinking Water Program Requirements.................................. 33Special Regulation Requirements ............................................ 34Selected Supplementary Readings ........................................... 39
Chapter 2 Water Quality Monitoring ....................................................... 41Sampling.................................................................................. 41Monitoring for Chemical Contaminants ................................. 58Laboratory Certification ......................................................... 59Record Keeping and Sample Labeling..................................... 61Sample Preservation, Storage, and Transportation ................. 62Selected Supplementary Readings ........................................... 65
Chapter 3 Water Laboratory Equipment and Instruments ......................... 67Labware .................................................................................. 67Major Laboratory Equipment ................................................. 78Safety Equipment .................................................................... 85Support Equipment ................................................................. 90Analytical Laboratory Instruments ......................................... 94Selected Supplementary Readings .......................................... 106
Chapter 4 Microbiological Contaminants ................................................ 107History ................................................................................... 107Indicator Organisms............................................................... 111Heterotrophic Plate Count (HPC) Procedure ......................... 118Selected Supplementary Readings .......................................... 120
Chapter 5 Physical and Aggregate Properties of Water ........................... 123Acidity.................................................................................... 123Alkalinity................................................................................ 124Calcium Carbonate Stability .................................................. 125Coagulent Effectiveness.......................................................... 127Color ...................................................................................... 132Conductivity........................................................................... 133Hardness................................................................................. 134Taste and Odor....................................................................... 135
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VI WATER QUALITY
Temperature........................................................................... 139Total Dissolved Solids............................................................ 140Turbidity ................................................................................ 140Selected Supplementary Readings .......................................... 143
Chapter 6 Inorganic Chemicals ................................................................145Carbon Dioxide ..................................................................... 145Chlroine Residual and Demand ............................................. 146Disinfection By-Products ....................................................... 148Dissolved Oxygen................................................................... 150Inorganic Metals .................................................................... 151Fluoride ................................................................................. 153Iron ........................................................................................ 154Manganese ............................................................................. 155Selected Supplementary Readings .......................................... 157
Chapter 7 Organic Contaminants ............................................................159Natural Organic Substances................................................... 159Synthetic Organic Substances................................................. 162Health Effects of Organic Chemicals...................................... 162Measurement of Organic Compounds ................................... 163Selected Supplementary Readings .......................................... 167
Chapter 8 Radiological Contaminants .....................................................169Radioactive Materials ............................................................ 169Radioactive Contaminants in Water ...................................... 171Adverse Health Effects of Radioactivity ................................ 173Radionuclide Monitoring Requirements................................ 173Selected Supplementary Readings .......................................... 175
Chapter 9 Customer Inquiries and Complaint Investigation ......................177General Principles .................................................................. 177Specific Complaints................................................................ 179Selected Supplementary Readings .......................................... 185
Glossary .................................................................................................................187Index......................................................................................................................207
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vii
Foreword
Water Quality is part four in a five-part series titled Principles and Practices of Water Sup-ply Operations. It contains information required by treatment system operators on drink-ing water regulations and water quality sampling and monitoring and describes thelaboratory equipment and instrumentation used today to analyze drinking water formicrobiological, chemical, and physical contaminants.
The other books in the series are
Water SourcesWater TreatmentWater Transmission and DistributionBasic Science Concepts and Applications (a reference handbook)
References are made to the other books in the series where appropriate in the text.The reference handbook is a companion to all four books. It contains basic reviews of
mathematics, hydraulics, chemistry, and electricity needed for the problems and computa-tions required in water supply operation. The handbook also uses examples to explain anddemonstrate many specific problems.
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ix
Acknowledgments
This fourth edition of Water Quality has been revised to include the latest available infor-mation on new analytical techniques and current federal drinking water regulations. Thematerial has also been reorganized for better coordination with the other books in theseries. The author of the revision was Joseph A. Ritter (B.S. Chemistry and certified WaterTreatment Operator). Special thanks go to Dr. Charles D. Hertz, Ph.D., Aqua America,Inc. and Dr. Jennifer L. Clancy, Ph.D., Clancy Environmental Consultants, Inc. for theirreview of the manuscript.
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xi
Introduction
Water treatment plant operators are required to understand federal, state and local lawsand the standards that apply to domestic water treatment systems. They should under-stand how drinking water regulations are administered and why compliance is essential toproviding safe drinking water to the public. Potable water treatment is a health relatedindustry.
Drinking water regulations set the treatment goals for the water supply industry.Their intent is to ensure uniform delivery of safe and aesthetically pleasing drinking waterto the public.
Drinking water regulations specify monitoring requirements, and water system opera-tors are responsible for two types of monitoring: 1) monitoring required to ensure that thewater is safe for human consumption, i.e., the water is potable [compliance monitoring];and 2) monitoring to measure the efficiency of treatment processes [process monitoring ortesting].
Water treatment plant operators are responsible for the proper sampling, i.e., theproper collection and preservation, and in some cases, the basic microbiological andchemical analyses of these samples.
This book contains nine chapters. Federal, state and local regulations continue tobecome more stringent and complicated. Chapter 1 provides a brief but thorough discus-sion of the Safe Drinking Water Act and federal drinking water regulations in effect as ofpublication of this fourth edition. Information on the regulations and suggested readingsources are provided for additional information.
Each water system operator should have access to the latest Federal and state drink-ing water regulations. These documents will detail the specific requirements that must bemet and the methods of water system operation, monitoring, and reporting required bythe Federal and state primacy agencies. Care must be taken to learn the specifics of theprimacy agency for each regulation in your specific geographical area, since some regula-tions now fall to the county or local levels for primary enforcement. The increasingcomplexity of the regulations and who has primacy over which regulation under varyingcircumstances has added to the operator’s burden of compliance. In some areas utilitiesare now having reporting regulations imposed on them by non-health related organiza-tions such as public utility commissions.
Water quality analysis is an important part of the operation of every public water system.Chapter 2 discusses the basics of proper sampling and monitoring.
Large water systems usually have access to comprehensive onsite laboratories.Maintaining an onsite, dedicated laboratory requires a substantial capital investment inequipment and technicians trained to perform the various analyses. Medium size sys-tems often have small laboratories with the capability to perform less complicated anal-yses. Small systems generally send samples to a state or commercial laboratory formicrobiological and chemical analyses. Chapter 3 describes the equipment and instru-mentation used in water analyses.
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XII WATER QUALITY
Water system operators are required to perform basic water analyses and to interpretthe test results. Chapters 4, 5, 6, 7, and 8 discuss the techniques commonly used to charac-terize drinking water.
Chapter 9 provides valuable suggestions for customer complaint and water qualityinquiry investigation.
Additional information on equipment, reagents, and detailed test procedures to con-duct each test can be found in either of the following references:
• Standard Methods for the Examination of Water and Wastewater (most recent edition).• Methods of Chemical Analyses for Water and Wastes, USEPA, Office of Technology
(most recent edition).
Simplified procedures for the more common tests are also provided in the followingpublications:
• AWWA Manual M12, Simplified Procedures for Water Examination (most recentedition).
• Several laboratory equipment manufacturers and suppliers have prepared handbooksthat outline the required equipment, reagents, and common test procedures.
It should be noted that all procedures, methods or any related reporting should be incompliance with the agency that has primacy for your specific region, since these regula-tions and requirements can vary from one state to another.
SELECTED SUPPLEMENTARY READINGSManual M12, Simplified Procedures for Water Examination. 2002. Denver, CO:
American Water Works Association.
Methods of Chemical Analyses of Water and Wastes. 1984. 600/4-79-020. Cincinnati,Ohio: US Environmental Protection Agency. [NOTE: This is an older manual thatmay not be available, Check the EPA web site for updated methods. http://www.epa.gov/safewater/regs.html#proposed ]
Standard Methods for the Examination of Water and Wastewater. 21st ed. 1998. A.D.Eaton, L.S. Clesceri, and A.E. Greenberg, eds. Washington D.C.: American PublicHealth Association, American Water Works Association, and Water EnvironmentFederation.
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1
C H A P T E R 1
Public Water Supply Regulations
The Safe Drinking Water Act (SDWA), passed by Congress and signed into law in 1974,started a new era in the field of public water supply. The number of water systems subjectto state and federal regulations has vastly increased, and the complexity of the regulationsthat must now be met far exceeds what could have been imagined just a few years ago. Inaddition, public water systems are subject to many additional state, local, and federalenvironmental and safety regulations.
SAFE DRINKING WATER ACTThe principal law governing drinking water safety in the United States is the SDWA.SDWA was passed by Congress and signed into law in 1974. Suspected carcinogens discov-ered in the drinking water of the United States established a widespread sense of urgencythat led to its passage. SDWA directs the US Environmental Protection Agency (USEPA)to promulgate and enforce National Primary Drinking Water Regulations (NPDWRs) thatcover more than 92 contaminants, ensuring safe drinking water for the consumer and pro-tecting public health. These include turbidity, 8 microbial or indicator organisms, 4 radio-nuclides (unless you are determined to be at risk; then 3 more are added), 32 inorganiccontaminants including the secondary standards and the disinfection by-products (DBPs)if applicable, and more than 60 organic contaminants including synthetic organic com-pounds (SOC), volatile organic compounds (VOC), and DBP compounds. There are alsomyriad regulations on plant operation, personnel qualified to operate a water system, andrelationships with customers. These are set not only by the USEPA but by state and localregulatory bodies, and operators must be knowledgeable about all of these regulations.
Under SDWA, USEPA sets legal limits on the levels of certain contaminants in drink-ing water. The legal limits reflect both the level that protects human health and the levelwater systems can achieve using the best available technology (BAT). Besides prescribingthese legal limits, USEPA rules set water testing schedules and methods that water systemsmust follow. The rules also list acceptable techniques for treating contaminated water.SDWA gives individual states the opportunity to set and enforce their own drinking waterstandards if the standards are at least as stringent as USEPA’s national standards. Moststates and territories directly oversee the water systems within their borders.
The requirements of the SDWA are applicable to all 50 states, the District of Colum-bia, Indian lands, Puerto Rico, the Virgin Islands, American Samoa, Guam, the Com-monwealth of the Northern Mariana Islands, and the Republic of Palau. The intent of theSDWA is for each state to accept primary enforcement responsibility (primacy) for theoperation of the state’s drinking water program. Indian tribes may also be delegatedprimacy for administration of public water supplies on tribal lands. As of 1994, all the
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2 WATER QUALITY
states and territories except Wyoming and the District of Columbia had accepted primacy.Only a few of the larger Indian tribes have accepted primacy.
SDWA was amended six times between 1974 and 1986 and again in 1996 and 1999.The 1986 SDWA amendments set up a timetable under which USEPA was required to
develop primary standards for 83 contaminants. Other major provisions required USEPA to
1. Define an approval treatment technique for each regulated contaminant,2. Specify criteria for filtration of surface water supplies,3. Specify criteria for disinfecting surface water and groundwater supplies, and4. Prohibit the use of lead products in materials used to convey drinking water.
In April 1993, the largest waterborne disease outbreak in the United States occurredin Milwaukee, Wisconsin, when an estimated 403,000 people were affected by the proto-zoan parasite Cryptosporidium parvum. This event attracted national attention to theimportance of safe drinking water and influenced the current theme of regulations. The1996 amendments revised the contaminant list and regulatory process.
On August 6, 1996, new SDWA amendments were signed into Public Law 104-182.These amendments created several new programs and included a total authorization ofmore than $12 billion in federal funds for drinking water programs. A section was addedto the regulations to clarify the standardization of operator certification programs by theprimacy agencies. A panel was formed to set policy so that all states, territories, and tribeshave a minimum set of requirements for certified water treatment operators. The regula-tions that came out in 1999 gave the states the power to create their own separate pro-grams as long as certain requirements were met. This included a minimum of a highschool diploma or equivalent for the operator, a grading for systems by size and technol-ogy, mandatory testing of operators, and mandatory continuing education tied to a certifi-cation renewal that was not to exceed a three year cycle. There was also to be anenforcement policy to suspend or revoke certification including criminal and civil actions.Grandfathering for site-specific operators was to be allowed as determined by the primacyagency with the owner of the system applying for the certification for the system’s opera-tors; these certifications would be nontransferable to other persons or other treatmentfacilities. The grandfathered operators had to meet all the requirements for the class ofcertification for renewal. The rules further stipulated that the system had to have an oper-ator for the size and level of treatment, and if the system was upgraded or the technologychanged, the operator had to be tested and upgraded before he could operate the changes.
Public Water SystemsUSEPA has further divided public water systems (PWS) that are covered by SDWArequirements into three categories based on the type of customers served, as follows:
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PUBLIC WATER SUPPLY REGULATIONS 3
1. Community public water systems (CWS) serve year-round residents and includemunicipal systems, mobile home parks, and apartment buildings with their own watersystem serving 15 or more units or 25 or more people.
2. Nontransient, noncommunity public water systems (NTNCWS) are entities with theirown water supply serving an average of at least 25 persons who do not live at the loca-tion but who use the water for more than six months per year. These systems includeschools and office buildings.
3. Transient, noncommunity public water systems (TNCWS) are establishments that havetheir own water system, where an average of at least 25 people per day visit and usethe water occasionally or for only short periods of time. Examples include restau-rants, hotels, motels, churches, and parks.
A public water system covered under the provisions of the SDWA supplies pipedwater for human consumption and has at least 15 service connections or serves 25 or morepersons 60 or more days each year.
Examples of systems that do not fall under the provisions of the act are private homeson their own wells, housing developments, condominiums, and apartments that each havefewer than 15 connections and serve fewer than 25 residents. Summer camps with a watersource that operates fewer than 60 days a year are also included. These systems are usuallycovered to some degree by state, county, or local health regulations.
Figure 1-1 provides examples of the types of water systems or establishments that arecovered under each category. The rationale for dividing systems into these three groups isthe chemical exposure of persons using the water. Most chemical contaminants only causeadverse health effects after long-term exposure. Brief exposure of an individual to low lev-els of a chemical contaminant may not have an effect.
FIGURE 1-1 Classification of public water systems
PublicWater
System
CommunityWater Systems
– Municipal Systems– Rural Water Districts– Mobile Home Parks
– Schools– Factories– Office Buildings
– Parks– Motels– Restaurants– Churches
Nontransient,NoncommunityWater Systems
Transient,NoncommunityWater Systems
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4 WATER QUALITY
Consider a municipal water system or mobile home park water supply contaminatedwith a low concentration of a carcinogen, a chemical known to cause cancer. A personwho drinks this water every day for a period of years theoretically has an increased chanceof getting cancer. A person who works in an office building that has a water supply con-taminated by a carcinogen may experience adverse health effects if the person drinks thecontaminated water over an extended period of time. A person who visits a hotel anddrinks the same contaminated water will only drink a small amount of contaminatedwater and will have a lower risk of contracting cancer.
Monitoring requirements for community and nontransient, noncommunity water sys-tems apply to all contaminants considered a health threat. Transient, noncommunity sys-tems are only required to monitor for contaminants currently considered to pose apotential health threat from brief exposure, such as nitrite and nitrate and microbiologicalcontaminants.
Approximately 155,000 public water systems in the United States are regulated underUSEPA and SDWA rules. About 52,000 are classed as community systems, andapproximately103,000 fall under one of the two noncommunity systems.
The USEPA classifies community public water systems according to the number ofcustomers they serve, the source of water and whether the service is year round or on anoccasional or seasonal basis.
• Very small systems serve fewer than 25 to 500 people, constitute 56 percent of the com-munity water systems, and serve 2 percent of the community water system population.
• Small systems serve 501 to 3,300 people, constitute 27 percent of the community watersystems, and serve 7 percent of the community water system population.
• Medium systems serve 3,301 to 10,000 people, constitute 9 percent of the communitywater systems, and serve 10 percent of the community water system population.
• Large systems serve 10,001 to 100,000 people, constitute 7 percent of the communitywater systems, and serve 36 percent of the community water system population.
• Very large systems serve more than 100,001 customers, constitute 1 percent of thecommunity water systems, and serve 46 percent of the community water system popu-lation. (Data are from USEPA’s FACTOIDS: Drinking Water and Ground Water Sta-tistics for 2008.)
National Primary Drinking Water RegulationsNPDWRs specify maximum contaminant levels (MCLs) or treatment techniques (TTs)for contaminants that may have an adverse health effect on humans. The primary regula-tions are mandatory, and all public water systems must comply with them. If analysis ofthe water produced by a water system indicates that an MCL for a contaminant isexceeded, the water system must initiate a treatment regime to reduce the contaminantconcentration to below the MCL or take appropriate steps to protect the public’s health.
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PUBLIC WATER SUPPLY REGULATIONS 5
Table 1-1 lists the status of USEPA primary drinking water standards at the time thisbook was prepared, and Table 1-2 describes the required sampling. (Some of the specialmonitoring for the Stage 2 Disinfectant/Disinfection By-Products (D/DBP2) Rule andother rules is not shown in Table 1-2. The final result of the monitoring will differ for eachsystem depending on the results of the preliminary sampling.)
Maximum contaminant level goalsThe maximum contaminant level goal (MCLG) is the concentration or level of a contam-inant in drinking water below which there is no known or expected risk to health. MCLGsallow for a margin of safety and are nonenforceable public health goals. An MCLG isdetermined using a combination of animal studies and human exposure data. It is the goalthe experts would like to see achieved for complete protection of public health.
In some cases the MCLG is economically achievable, and in other instances it is not.For noncarcinogens, the MCLG is a finite number. For known or suspected human car-cinogens, the MCLG is zero.
Maximum contaminant levelsThe MCL is the highest level of a contaminant allowed in drinking water. MCLs areenforceable standards. SDWA attempts to establish an MCL and an MCLG for eachdrinking water contaminant. The MCL is set at a level as close as possible to the MCLGbut at a concentration that is reasonable and economically achievable with BAT. When itis impossible or impractical to establish an MCL, the USEPA can establish a TT and spec-ify treatment methods that must be used to minimize exposure of the public. ExistingMCLs are adjusted from time to time as improved treatment technologies and laboratorytesting methods are developed and it becomes economically feasible to move the MCLcloser to the MCLG. An MCL may be changed if new health effects data indicate that thereduction or increase in the allowable levels will not harm the population.
Compliance with the MCL levels varies by the contaminant and can be based on asingle sample or running annual averages (RAA).
Maximum residual disinfectant level goal (MRDL/MRDLG). For chlorine, chloram-ines, and chlorine dioxide, the MRDL and the MRDLG have been set to the same level thatis 4.0 mg/L for chlorine and chloramines and 0.8 mg/L for chlorine dioxide—the level of adrinking water disinfectant below which there is no known expected risk to health. Theselevels are monitored at the tap of the user; thus, more could be present on leaving the treat-ment facility as needed. MRDLGs do not reflect the benefits of a disinfectant used to con-trol microorganisms.
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6 WATER QUALITY
Tab
le c
onti
nued
nex
t pa
ge
TABL
E 1-
1 L
ist o
f con
tam
inan
ts a
nd th
eir M
CLs
Con
tam
inan
tM
CL
G,*
mg/
L†
MC
L o
r T
T,
mg/
LPo
tent
ial H
ealt
h E
ffec
ts F
rom
In
gest
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of W
ater
Sour
ces
of C
onta
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in
Dri
nkin
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Mic
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gani
sms
Cry
ptos
pori
dium
Zer
oT
T‡
Gas
troi
ntes
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l illn
ess
(e.g
., di
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ram
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ptos
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and
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mal
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al w
aste
Gia
rdia
lam
blia
Zer
oT
TG
astr
oint
estin
al il
lnes
s (e
.g.,
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, vo
miti
ng, c
ram
ps),
Gia
rdia
sis
Hum
an a
nd a
nim
al f
ecal
was
te
Het
erot
roph
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late
cou
nt
(HP
C)
N/A
TT
HP
C h
as n
o he
alth
eff
ects
; it
is a
n an
a-ly
tic
met
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used
to
mea
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var
i-et
y of
bac
teri
a th
at a
re c
omm
on in
w
ater
. The
low
er t
he c
once
ntra
tion
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eria
in d
rink
ing
wat
er, t
he b
ette
r m
aint
aine
d th
e w
ater
sys
tem
is.
HP
C m
easu
res
a ra
nge
of b
acte
ria
that
ar
e na
tura
lly p
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the
en
viro
nmen
t
Leg
ione
llaZ
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TT
Leg
ionn
aire
’s d
isea
se, a
typ
e of
pn
eum
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Fou
nd n
atur
ally
in w
ater
; mul
tipl
ies
in
heat
ing
syst
ems
Tota
l col
iform
s (in
clud
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feca
l col
iform
and
E. c
oli)
Zer
o5.
0%**
Not
a h
ealt
h th
reat
in it
self
; it
is u
sed
to
indi
cate
whe
ther
oth
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oten
tial
ly
harm
ful b
acte
ria
may
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††
Col
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tura
lly p
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e fr
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hum
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nd a
nim
al f
ecal
was
te.
WaterQuality.book Page 6 Friday, April 30, 2010 2:46 PM
PUBLIC WATER SUPPLY REGULATIONS 7
Tab
le c
onti
nued
nex
t pa
ge
Tur
bidi
tyN
/AT
TT
urbi
dity
is a
mea
sure
of
the
clou
dine
ss
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ater
. It
is u
sed
to in
dica
te w
ater
qu
alit
y an
d fil
trat
ion
effe
ctiv
enes
s (e
.g.,
whe
ther
dis
ease
-cau
sing
org
anis
ms
are
pres
ent)
. Hig
her
turb
idit
y le
vels
are
of
ten
asso
ciat
ed w
ith
high
er le
vels
of
dise
ase-
caus
ing
mic
roor
gani
sms
such
as
vir
uses
, par
asit
es, a
nd s
ome
bact
eria
. T
hese
org
anis
ms
can
caus
e sy
mpt
oms
such
as
naus
ea, c
ram
ps, d
iarr
hea,
and
as
soci
ated
hea
dach
es.
Soil
runo
ff
Vir
uses
(en
teri
c)Z
ero
TT
Gas
troi
ntes
tina
l illn
ess
(e.g
., di
arrh
ea,
vom
itin
g, c
ram
ps)
Hum
an a
nd a
nim
al f
ecal
was
te
Dis
infe
ctio
n B
y-P
rodu
cts
Bro
mat
eZ
ero
0.01
0In
crea
sed
risk
of
canc
erB
y-pr
oduc
t of d
rink
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wat
er d
isin
fect
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wit
h oz
one
Chl
orit
e0.
81.
0A
nem
ia; n
ervo
us s
yste
m e
ffec
ts in
infa
nts
and
youn
g ch
ildre
nB
y-pr
oduc
t of d
rink
ing
wat
er d
isin
fect
ion
chlo
rine
dio
xide
Hal
oace
tic
acid
s (H
AA
5)N
/A‡‡
0.06
0In
crea
sed
risk
of
canc
erB
y-pr
oduc
t of
dri
nkin
g w
ater
dis
infe
ctio
n
Tota
l tri
halo
met
hane
s (T
TH
Ms)
Non
e***
0.08
0 L
iver
, kid
ney,
or
cent
ral n
ervo
us s
yste
m
prob
lem
s; in
crea
sed
risk
of
canc
erB
y-pr
oduc
t of
dri
nkin
g w
ater
dis
infe
ctio
n
Dis
infe
ctan
ts
Chl
oram
ines
(as
Cl 2
)M
RD
LG
=4
MR
DL
=4.
0E
ye/n
ose
irri
tati
on; s
tom
ach
disc
omfo
rt;
anem
iaW
ater
add
itiv
e us
ed t
o co
ntro
l mic
robe
s
TABL
E 1-
1 L
ist o
f con
tam
inan
ts a
nd th
eir M
CLs
(Co
ntin
ued)
Con
tam
inan
tM
CL
G,*
mg/
L†
MC
L o
r T
T,
mg/
LPo
tent
ial H
ealt
h E
ffec
ts F
rom
In
gest
ion
of W
ater
Sour
ces
of C
onta
min
ant
in
Dri
nkin
g W
ater
WaterQuality.book Page 7 Friday, April 30, 2010 2:46 PM
8 WATER QUALITY
Tab
le c
onti
nued
nex
t pa
ge
Chl
orin
e (a
s C
l 2)
MR
DL
G=
4M
RD
L=
4.0
Eye
/nos
e ir
rita
tion
; sto
mac
h di
scom
fort
Wat
er a
ddit
ive
used
to
cont
rol m
icro
bes
Chl
orin
e di
oxid
e (a
s C
lO2)
MR
DL
G=
0.8
MR
DL
=0.
8A
nem
ia; n
ervo
us s
yste
m e
ffec
ts in
infa
nts
and
youn
g ch
ildre
nW
ater
add
itiv
e us
ed t
o co
ntro
l mic
robe
s
Inor
gani
c C
hem
ical
s
Ant
imon
y0.
006
0.00
6In
crea
se in
blo
od c
hole
ster
ol; d
ecre
ase
in
bloo
d su
gar
Dis
char
ge f
rom
pet
role
um r
efin
erie
s; fi
re
reta
rdan
ts; c
eram
ics;
ele
ctro
nics
; new
le
ad-f
ree
sold
er
Ars
enic
00.
010
as o
f 1/
23/0
6Sk
in d
amag
e or
pro
blem
s w
ith
circ
ulat
ory
syst
ems;
pos
sibl
e in
crea
sed
risk
of
con-
trac
ting
can
cer
Ero
sion
of
natu
ral d
epos
its;
run
off
from
or
char
ds, r
unof
f fr
om g
lass
and
ele
c-tr
onic
s pr
oduc
tion
was
tes
Asb
esto
s (f
iber
>10
mic
rom
eter
s)7
mill
ion
fiber
s pe
r lit
er (
MF
L)
7 M
FL
Incr
ease
d ri
sk o
f de
velo
ping
ben
ign
inte
stin
al p
olyp
sD
ecay
of a
sbes
tos
cem
ent i
n w
ater
mai
ns;
eros
ion
of n
atur
al d
epos
its
Bar
ium
22
Incr
ease
in b
lood
pre
ssur
eD
isch
arge
of d
rilli
ng w
aste
s; d
isch
arge
fr
om m
etal
ref
iner
ies;
ero
sion
of n
atur
al
depo
sits
Ber
ylliu
m0.
004
0.00
4In
test
inal
lesi
ons
Dis
char
ge fr
om m
etal
ref
iner
ies
and
coal
-bu
rnin
g fa
ctor
ies;
dis
char
ge fr
om e
lect
ri-
cal,
aero
spac
e, a
nd d
efen
se in
dust
ries
Cad
miu
m0.
005
0.00
5K
idne
y da
mag
eC
orro
sion
of
galv
aniz
ed p
ipes
; ero
sion
of
natu
ral d
epos
its;
dis
char
ge f
rom
met
al
refin
erie
s; r
unof
f fr
om w
aste
bat
teri
es
and
pain
ts
TABL
E 1-
1 L
ist o
f con
tam
inan
ts a
nd th
eir M
CLs
(Co
ntin
ued)
Con
tam
inan
tM
CL
G,*
mg/
L†
MC
L o
r T
T,
mg/
LPo
tent
ial H
ealt
h E
ffec
ts F
rom
In
gest
ion
of W
ater
Sour
ces
of C
onta
min
ant
in
Dri
nkin
g W
ater
WaterQuality.book Page 8 Friday, April 30, 2010 2:46 PM
PUBLIC WATER SUPPLY REGULATIONS 9
Tab
le c
onti
nued
nex
t pa
ge
Chr
omiu
m (
tota
l)0.
10.
1A
llerg
ic d
erm
atit
isD
isch
arge
fro
m s
teel
and
pul
p m
ills;
er
osio
n of
nat
ural
dep
osit
s
Cop
per
1.3
TT
††† ; a
ctio
n le
vel=
1.3
Shor
t-te
rm e
xpos
ure:
gas
troi
ntes
tina
l di
stre
ssL
ong-
term
exp
osur
e: li
ver
or k
idne
y da
mag
eP
eopl
e w
ith
Wils
on’s
dise
ase
shou
ld c
on-
sult
thei
r pe
rson
al d
octo
r if
the
amou
nt
of c
oppe
r in
the
ir w
ater
exc
eeds
the
ac
tion
leve
l
Cor
rosi
on o
f ho
useh
old
plum
bing
sys
-te
ms;
ero
sion
of
natu
ral d
epos
its
Cya
nide
(as
fre
e cy
anid
e)0.
20.
2N
erve
dam
age
or t
hyro
id p
robl
ems
Dis
char
ge f
rom
ste
el/m
etal
fac
tori
es; d
is-
char
ge f
rom
pla
stic
s an
d fe
rtili
zer
fact
orie
s
Flu
orid
e4.
04.
0B
one
dise
ase
(pai
n an
d te
nder
ness
of
the
bone
s); c
hild
ren
may
get
mot
tled
tee
thW
ater
add
itive
that
pro
mot
es s
tron
g te
eth;
er
osio
n of
nat
ural
dep
osits
; dis
char
ge
from
fert
ilize
r an
d al
umin
um fa
ctor
ies
Lea
dZ
ero
TT
; act
ion
leve
l=0.
015
Infa
nts
and
child
ren:
Del
ays
in p
hysi
cal
or m
enta
l dev
elop
men
t; c
hild
ren
coul
d sh
ow s
light
def
icit
s in
att
enti
on s
pan
and
lear
ning
abi
litie
sA
dult
s: K
idne
y pr
oble
ms;
hig
h bl
ood
pres
sure
Cor
rosi
on o
f hou
seho
ld p
lum
bing
sys
-te
ms;
ero
sion
of n
atur
al d
epos
its
Mer
cury
(in
orga
nic)
0.00
20.
002
Kid
ney
dam
age
Ero
sion
of
natu
ral d
epos
its;
dis
char
ge
from
ref
iner
ies
and
fact
orie
s; r
unof
f fr
om la
ndfil
ls a
nd c
ropl
ands
TABL
E 1-
1 L
ist o
f con
tam
inan
ts a
nd th
eir M
CLs
(Co
ntin
ued)
Con
tam
inan
tM
CL
G,*
mg/
L†
MC
L o
r T
T,
mg/
LPo
tent
ial H
ealt
h E
ffec
ts F
rom
In
gest
ion
of W
ater
Sour
ces
of C
onta
min
ant
in
Dri
nkin
g W
ater
WaterQuality.book Page 9 Friday, April 30, 2010 2:46 PM
10 WATER QUALITY
Tab
le c
onti
nued
nex
t pa
ge
Nit
rate
(m
easu
red
as
nitr
ogen
)10
10In
fant
s be
low
the
age
of
six
mon
ths
who
dr
ink
wat
er c
onta
inin
g ni
trat
e in
exc
ess
of t
he M
CL
cou
ld b
ecom
e se
riou
sly
ill
and,
if u
ntre
ated
, may
die
. Sym
ptom
s in
clud
e sh
ortn
ess
of b
reat
h an
d bl
ue-
baby
syn
drom
e.
Run
off
from
fer
tiliz
er u
se; l
each
ing
from
se
ptic
tan
ks, s
ewag
e; e
rosi
on o
f na
tura
l de
posi
ts
Nit
rite
(m
easu
red
as
nitr
ogen
)1
1In
fant
s be
low
the
age
of
six
mon
ths
who
dr
ink
wat
er c
onta
inin
g ni
trit
e in
exc
ess
of t
he M
CL
cou
ld b
ecom
e se
riou
sly
ill
and,
if u
ntre
ated
, may
die
. Sym
ptom
s in
clud
e sh
ortn
ess
of b
reat
h an
d bl
ue-
baby
syn
drom
e.
Run
off
from
fer
tiliz
er u
se; l
each
ing
from
se
ptic
tan
ks, s
ewag
e; e
rosi
on o
f na
tura
l de
posi
ts
Sele
nium
0.05
0.05
Hai
r or
fing
erna
il lo
ss; n
umbn
ess
in fi
nger
s or
toes
; cir
cula
tory
pro
blem
sD
isch
arge
from
pet
role
um r
efin
erie
s; e
ro-
sion
of n
atur
al d
epos
its; d
isch
arge
from
m
ines
Tha
llium
0.00
050.
002
Hai
r lo
ss; c
hang
es in
blo
od; k
idne
y,
inte
stin
e, o
r liv
er p
robl
ems
Lea
chin
g fr
om o
re-p
roce
ssin
g si
tes;
dis
-ch
arge
from
ele
ctro
nics
, gla
ss, a
nd d
rug
fact
orie
s
Org
anic
Che
mic
als
Syn
thet
ic O
rgan
ic
Che
mic
als
(SO
Cs)
2,4,
5-T
P (
Silv
ex)
0.05
0.05
Liv
er p
robl
ems
Res
idue
of
bann
ed h
erbi
cide
2,4-
D0.
070.
07K
idne
y, li
ver,
or a
dren
al g
land
pro
blem
sR
unof
f fr
om h
erbi
cide
use
d on
row
cro
ps
Acr
ylam
ide
Zer
oT
T‡‡
‡N
ervo
us s
yste
m o
r bl
ood
prob
lem
s;
incr
ease
d ri
sk o
f ca
ncer
Add
ed to
wat
er d
urin
g se
wag
e/w
aste
wat
er
trea
tmen
t
TABL
E 1-
1 L
ist o
f con
tam
inan
ts a
nd th
eir M
CLs
(Co
ntin
ued)
Con
tam
inan
tM
CL
G,*
mg/
L†
MC
L o
r T
T,
mg/
LPo
tent
ial H
ealt
h E
ffec
ts F
rom
In
gest
ion
of W
ater
Sour
ces
of C
onta
min
ant
in
Dri
nkin
g W
ater
WaterQuality.book Page 10 Friday, April 30, 2010 2:46 PM
PUBLIC WATER SUPPLY REGULATIONS 11
Tab
le c
onti
nued
nex
t pa
ge
Ala
chlo
rZ
ero
0.00
2E
ye, l
iver
, kid
ney,
or
sple
en p
robl
ems;
an
emia
; inc
reas
ed r
isk
of c
ance
rR
unof
f fr
om h
erbi
cide
use
d on
row
cro
ps
Atr
azin
e0.
003
0.00
3C
ardi
ovas
cula
r sy
stem
or
repr
oduc
tive
pr
oble
ms
Run
off
from
her
bici
de u
sed
on r
ow c
rops
Ben
zo(a
)pyr
ene
(PA
Hs)
Zer
o0.
0002
Rep
rodu
ctiv
e di
ffic
ulti
es; i
ncre
ased
ris
k of
canc
er
Lea
chin
g fr
om li
ning
s of
wat
er s
tora
ge
tank
s an
d di
stri
buti
on li
nes
Car
bofu
ran
0.04
0.04
Pro
blem
s w
ith
bloo
d, n
ervo
us s
yste
m,
orre
prod
ucti
ve s
yste
mL
each
ing
of s
oil f
umig
ant
used
on
rice
an
d al
falf
a
Chl
orda
neZ
ero
0.00
2L
iver
or
nerv
ous
syst
em p
robl
ems;
in
crea
sed
risk
of
canc
er
Res
idue
of
bann
ed t
erm
itic
ide
Dal
apon
0.2
0.2
Min
or k
idne
y ch
ange
sR
unof
f fr
om h
erbi
cide
use
d on
rig
hts-
of-
way
Di(
2-et
hylh
exyl
) ad
ipat
e0.
40.
4W
eigh
t lo
ss; l
iver
pro
blem
s; p
ossi
ble
repr
oduc
tive
diff
icul
ties
Dis
char
ge f
rom
che
mic
al f
acto
ries
Di(
2-et
hylh
exyl
) ph
thal
ate
(DE
HP
)Z
ero
0.00
6R
epro
duct
ive
diff
icul
ties
; liv
er p
robl
ems;
in
crea
sed
risk
of
canc
erD
isch
arge
fro
m r
ubbe
r an
d ch
emic
al
fact
orie
s
1,2-
Dib
rom
o-3-
chlo
ro-
prop
ane
(DB
CP
)Z
ero
0.00
02R
epro
duct
ive
diff
icul
ties
; inc
reas
ed r
isk
of c
ance
rR
unof
f/le
achi
ng f
rom
soi
l fum
igan
t us
ed
on s
oybe
ans,
cot
ton,
pin
eapp
les,
and
or
char
ds
Din
oseb
0.00
70.
007
Rep
rodu
ctiv
e di
ffic
ulti
esR
unof
f fr
om h
erbi
cide
use
d on
soy
bean
s an
d ve
geta
bles
Diq
uat
0.02
0.02
Cat
arac
tsR
unof
f fr
om h
erbi
cide
use
Dio
xin
(2,3
,7,8
-TC
DD
)Z
ero
0.00
0000
03R
epro
duct
ive
diff
icul
ties
; inc
reas
ed r
isk
ofca
ncer
E
mis
sion
s fr
om w
aste
inci
nera
tion
and
ot
her
com
bust
ion;
dis
char
ge f
rom
ch
emic
al f
acto
ries
TABL
E 1-
1 L
ist o
f con
tam
inan
ts a
nd th
eir M
CLs
(Co
ntin
ued)
Con
tam
inan
tM
CL
G,*
mg/
L†
MC
L o
r T
T,
mg/
LPo
tent
ial H
ealt
h E
ffec
ts F
rom
In
gest
ion
of W
ater
Sour
ces
of C
onta
min
ant
in
Dri
nkin
g W
ater
WaterQuality.book Page 11 Friday, April 30, 2010 2:46 PM
12 WATER QUALITY
Tab
le c
onti
nued
nex
t pa
ge
End
otha
ll0.
10.
1St
omac
h an
d in
test
inal
pro
blem
s R
unof
f fr
om h
erbi
cide
use
End
rin
0.00
20.
002
Liv
er p
robl
ems
Res
idue
of
bann
ed in
sect
icid
e
Epi
chlo
rohy
drin
Zer
oT
TIn
crea
sed
canc
er r
isk,
and
ove
r a
long
pe
riod
of
tim
e, s
tom
ach
prob
lem
sD
isch
arge
fro
m in
dust
rial
che
mic
al f
acto
-ri
es; a
n im
puri
ty o
f so
me
wat
er t
reat
-m
ent
chem
ical
s
Eth
ylen
e di
brom
ide
Zer
o0.
0000
5P
robl
ems
wit
h liv
er, s
tom
ach,
rep
rodu
c-ti
ve s
yste
m, o
r ki
dney
s; in
crea
sed
risk
of
can
cer
Dis
char
ge f
rom
pet
role
um r
efin
erie
s
Gly
phos
ate
0.7
0.7
Kid
ney
prob
lem
s; r
epro
duct
ive
diff
icul
ties
Run
off
from
her
bici
de u
se
Hep
tach
lor
Zer
o0.
0004
Liv
er d
amag
e; in
crea
sed
risk
of c
ance
rR
esid
ue o
f ba
nned
ter
mit
icid
e
Hep
tach
lor
epox
ide
Zer
o0.
0002
Liv
er d
amag
e; in
crea
sed
risk
of c
ance
rB
reak
dow
n of
hep
tach
lor
Hex
achl
orob
enze
neZ
ero
0.00
1L
iver
or
kidn
ey p
robl
ems;
rep
rodu
ctiv
e di
ffic
ulti
es; i
ncre
ased
ris
k of
can
cer
Dis
char
ge f
rom
met
al r
efin
erie
s an
d ag
ri-
cult
ural
che
mic
al f
acto
ries
Hex
achl
oroc
yclo
pent
-ad
iene
(H
EX
)0.
050.
05K
idne
y or
sto
mac
h pr
oble
ms
Dis
char
ge f
rom
che
mic
al f
acto
ries
Lin
dane
0.00
020.
0002
Liv
er o
r ki
dney
pro
blem
sR
unof
f/le
achi
ng f
rom
inse
ctic
ide
used
on
catt
le, l
umbe
r, ga
rden
s
Met
hoxy
chlo
r0.
040.
04R
epro
duct
ive
diff
icul
ties
R
unof
f/le
achi
ng f
rom
inse
ctic
ide
used
on
frui
ts, v
eget
able
s, a
lfal
fa, l
ives
tock
Oxa
myl
(V
ydat
e®)
0.2
0.2
Slig
ht n
ervo
us s
yste
m e
ffec
ts
Run
off/
leac
hing
fro
m in
sect
icid
e us
ed o
n ap
ples
, pot
atoe
s, a
nd t
omat
oes
Pen
tach
loro
phen
olZ
ero
0.00
1L
iver
or
kidn
ey p
robl
ems;
incr
ease
d ca
ncer
ris
kD
isch
arge
from
woo
d-pr
eser
ving
fact
orie
s
TABL
E 1-
1 L
ist o
f con
tam
inan
ts a
nd th
eir M
CLs
(Co
ntin
ued)
Con
tam
inan
tM
CL
G,*
mg/
L†
MC
L o
r T
T,
mg/
LPo
tent
ial H
ealt
h E
ffec
ts F
rom
In
gest
ion
of W
ater
Sour
ces
of C
onta
min
ant
in
Dri
nkin
g W
ater
WaterQuality.book Page 12 Friday, April 30, 2010 2:46 PM
PUBLIC WATER SUPPLY REGULATIONS 13
Tab
le c
onti
nued
nex
t pa
ge
Pic
lora
m0.
50.
5L
iver
pro
blem
s H
erbi
cide
run
off
Poly
chlo
rina
ted
biph
enyl
s (P
CB
s)Z
ero
0.00
05Sk
in c
hang
es; t
hym
us g
land
pro
blem
s;
imm
une
defic
ienc
ies;
rep
rodu
ctiv
e or
ne
rvou
s sy
stem
diff
icul
ties
; inc
reas
ed
risk
of
canc
er
Run
off
from
land
fills
; dis
char
ge o
f w
aste
ch
emic
als
Sim
azin
e0.
004
0.00
4P
robl
ems
wit
h bl
ood
Her
bici
de r
unof
f
Toxa
phen
eZ
ero
0.00
3K
idne
y, li
ver,
or t
hyro
id p
robl
ems;
in
crea
sed
risk
of
canc
erR
unof
f/le
achi
ng f
rom
inse
ctic
ide
used
on
cott
on a
nd c
attl
e
Vol
atile
Org
anic
Che
mic
als
(VO
Cs)
Ben
zene
Zer
o0.
005
Ane
mia
; dec
reas
e in
blo
od p
late
lets
; in
crea
sed
risk
of
canc
erD
isch
arge
fro
m f
acto
ries
; lea
chin
g fr
om
gas
stor
age
tank
s an
d la
ndfi
lls
Chl
orob
enze
ne0.
10.
1L
iver
or
kidn
ey p
robl
ems
Dis
char
ge fr
om c
hem
ical
and
agr
icul
tura
l ch
emic
al f
acto
ries
Car
bon
tetr
achl
orid
eZ
ero
0.00
5L
iver
pro
blem
s; in
crea
sed
risk
of
canc
erD
isch
arge
from
che
mic
al p
lant
s an
d ot
her
indu
stri
al a
ctiv
itie
s
o-D
ichl
orob
enze
ne0.
60.
6L
iver
, kid
ney,
or
circ
ulat
ory
syst
em
prob
lem
sD
isch
arge
from
indu
stri
al c
hem
ical
fact
orie
s
p-D
ichl
orob
enze
ne0.
075
0.07
5A
nem
ia; l
iver
, kid
ney,
or
sple
en d
amag
e;
chan
ges
in b
lood
Dis
char
ge fr
om in
dust
rial
che
mic
al fa
ctor
ies
1,2-
Dic
hlor
oeth
ane
Zer
o0.
005
Incr
ease
d ri
sk o
f ca
ncer
D
isch
arge
from
indu
stri
al c
hem
ical
fact
orie
s
1,1-
Dic
hlor
oeth
ylen
e0.
007
0.00
7L
iver
pro
blem
s D
isch
arge
from
indu
stri
al c
hem
ical
fact
orie
s
cis-
1,2-
Dic
hlor
oeth
ylen
e0.
070.
07L
iver
pro
blem
sD
isch
arge
from
indu
stri
al c
hem
ical
fact
orie
s
tran
s-1,
2-D
ichl
oroe
thyl
ene
0.1
0.1
Liv
er p
robl
ems
Dis
char
ge fr
om in
dust
rial
che
mic
al fa
ctor
ies
TABL
E 1-
1 L
ist o
f con
tam
inan
ts a
nd th
eir M
CLs
(Co
ntin
ued)
Con
tam
inan
tM
CL
G,*
mg/
L†
MC
L o
r T
T,
mg/
LPo
tent
ial H
ealt
h E
ffec
ts F
rom
In
gest
ion
of W
ater
Sour
ces
of C
onta
min
ant
in
Dri
nkin
g W
ater
WaterQuality.book Page 13 Friday, April 30, 2010 2:46 PM
14 WATER QUALITY
Tab
le c
onti
nued
nex
t pa
ge
Dic
hlor
omet
hane
Zer
o0.
005
Liv
er p
robl
ems;
incr
ease
d ri
sk o
f ca
ncer
D
isch
arge
from
dru
g an
d ch
emic
al fa
ctor
ies
1,2-
Dic
hlor
opro
pane
Zer
o0.
005
Incr
ease
d ri
sk o
f ca
ncer
Dis
char
ge fr
om in
dust
rial
che
mic
al fa
ctor
ies
Eth
ylbe
nzen
e0.
70.
7L
iver
or
kidn
ey p
robl
ems
Dis
char
ge f
rom
pet
role
um r
efin
erie
s
Styr
ene
0.1
0.1
Liv
er, k
idne
y, o
r ci
rcul
ator
y sy
stem
pr
oble
ms
Dis
char
ge f
rom
rub
ber
and
plas
tics
fac
to-
ries
; lea
chin
g fr
om la
ndfi
lls
Tet
rach
loro
ethy
lene
(P
CE
)Z
ero
0.00
5L
iver
pro
blem
s; in
crea
sed
risk
of
canc
erD
isch
arge
fro
m f
acto
ries
and
dry
cle
aner
s
Tolu
ene
11
Ner
vous
sys
tem
, kid
ney,
or
liver
pro
blem
sD
isch
arge
fro
m p
etro
leum
fac
tori
es
1,2,
4-T
rich
loro
benz
ene
0.07
0.07
Cha
nges
in a
dren
al g
land
sD
isch
arge
fro
m t
exti
le fi
nish
ing
fact
orie
s
1,1,
1-T
rich
loro
etha
ne0.
20.
2L
iver
, ner
vous
sys
tem
, or
circ
ulat
ory
prob
lem
s D
isch
arge
fro
m m
etal
deg
reas
ing
site
s an
d ot
her
fact
orie
s
1,1,
2-T
rich
loro
etha
ne0.
003
0.00
5L
iver
, kid
ney,
or
imm
une
syst
em p
robl
ems
Dis
char
ge fr
om in
dust
rial
che
mic
al fa
ctor
ies
Tri
chlo
roet
hyle
ne (
TC
E)
Zer
o0.
005
Liv
er p
robl
ems;
incr
ease
d ri
sk o
f ca
ncer
D
isch
arge
fro
m m
etal
deg
reas
ing
site
s an
d ot
her
fact
orie
s
Vin
yl c
hlor
ide
Zer
o0.
002
Incr
ease
d ri
sk o
f ca
ncer
Lea
chin
g fr
om P
VC
pip
es; d
isch
arge
from
pl
asti
cs f
acto
ries
Xyl
enes
(to
tal)
1010
Ner
vous
sys
tem
dam
age
Dis
char
ge f
rom
pet
role
um f
acto
ries
; dis
-ch
arge
fro
m c
hem
ical
fac
tori
es
TABL
E 1-
1 L
ist o
f con
tam
inan
ts a
nd th
eir M
CLs
(Co
ntin
ued)
Con
tam
inan
tM
CL
G,*
mg/
L†
MC
L o
r T
T,
mg/
LPo
tent
ial H
ealt
h E
ffec
ts F
rom
In
gest
ion
of W
ater
Sour
ces
of C
onta
min
ant
in
Dri
nkin
g W
ater
WaterQuality.book Page 14 Friday, April 30, 2010 2:46 PM
PUBLIC WATER SUPPLY REGULATIONS 15
Tab
le c
onti
nued
nex
t pa
ge
Rad
ionu
clid
es
Alp
ha p
arti
cles
Non
eZ
ero
15 p
icoc
urie
s pe
r lit
er
(pC
i/L)
Incr
ease
d ri
sk o
f ca
ncer
Ero
sion
of
natu
ral d
epos
its
of c
erta
in
min
eral
s th
at a
re r
adio
acti
ve a
nd m
ay
emit
a fo
rm o
f ra
diat
ion
know
n as
al
pha
radi
atio
n
Bet
a pa
rtic
les
and
phot
on
emit
ters
Non
eZ
ero
4 m
illir
ems
per
year
Incr
ease
d ri
sk o
f ca
ncer
Dec
ay o
f na
tura
l and
syn
thet
ic d
epos
its
of c
erta
in m
iner
als
that
are
rad
ioac
tive
an
d m
ay e
mit
form
s of
rad
iati
on
know
n as
pho
tons
and
bet
a ra
diat
ion
Rad
ium
226
and
rad
ium
22
8 (c
ombi
ned)
Non
eZ
ero
5 pC
i/LIn
crea
sed
risk
of
canc
erE
rosi
on o
f na
tura
l dep
osit
s
Ura
nium
Zer
o30
μg/
L a
s of
12
/8/0
3In
crea
sed
risk
of
canc
er, k
idne
y to
xici
tyE
rosi
on o
f na
tura
l dep
osit
s
*D
efin
itio
ns:
Max
imum
con
tam
inan
t le
vel (
MC
L)—
The
hig
hest
leve
l of
a co
ntam
inan
t th
at is
allo
wed
in d
rink
ing
wat
er. M
CL
s ar
e se
t as
clo
se t
o M
CL
Gs
as f
easi
ble
usin
g th
e be
st a
vaila
ble
trea
tmen
t te
chno
logy
and
tak
ing
cost
into
con
side
rati
on. M
CL
s ar
e en
forc
eabl
e st
anda
rds.
Max
imum
con
tam
inan
t lev
el g
oal (
MC
LG
)—T
he le
vel o
f a c
onta
min
ant i
n dr
inki
ng w
ater
bel
ow w
hich
ther
e is
no
know
n or
exp
ecte
d ri
sk to
hea
lth.
MC
LG
s al
low
fo
r a
mar
gin
of s
afet
y an
d ar
e no
nenf
orce
able
pub
lic h
ealt
h go
als.
Max
imum
res
idua
l dis
infe
ctan
t le
vel (
MR
DL
)—T
he h
ighe
st le
vel o
f a
disi
nfec
tant
allo
wed
in d
rink
ing
wat
er. T
here
is c
onvi
ncin
g ev
iden
ce t
hat
addi
tion
of
a di
sin-
fect
ant
is n
eces
sary
for
cont
rol o
f m
icro
bial
con
tam
inan
ts.
Max
imum
res
idua
l dis
infe
ctan
t le
vel g
oal (
MR
DL
G)—
The
leve
l of
a dr
inki
ng w
ater
dis
infe
ctan
t be
low
whi
ch t
here
is n
o kn
own
or e
xpec
ted
risk
to
heal
th.
MR
DL
Gs
do n
ot r
efle
ct t
he b
enef
its
of t
he u
se o
f di
sinf
ecta
nts
to c
ontr
ol m
icro
bial
con
tam
inan
ts.
Tre
atm
ent
Tec
hniq
ue (
TT
)—A
req
uire
d pr
oces
s in
tend
ed t
o re
duce
the
leve
l of
a co
ntam
inan
t in
dri
nkin
g w
ater
.†
Uni
ts a
re in
mill
igra
ms
per
liter
(m
g/L
) un
less
oth
erw
ise
note
d. M
illig
ram
s pe
r lit
er is
equ
ival
ent
to p
arts
per
mill
ion.
TABL
E 1-
1 L
ist o
f con
tam
inan
ts a
nd th
eir M
CLs
(Co
ntin
ued)
Con
tam
inan
tM
CL
G,*
mg/
L†
MC
L o
r T
T,
mg/
LPo
tent
ial H
ealt
h E
ffec
ts F
rom
In
gest
ion
of W
ater
Sour
ces
of C
onta
min
ant
in
Dri
nkin
g W
ater
WaterQuality.book Page 15 Friday, April 30, 2010 2:46 PM
16 WATER QUALITY‡
USE
PA’s
Sur
face
Wat
er T
reat
men
t R
ules
(SW
TR
s) r
equi
re s
yste
ms
usin
g su
rfac
e w
ater
or
grou
ndw
ater
und
er t
he d
irec
t in
flue
nce
of s
urfa
ce w
ater
to
(1)
disi
nfec
t th
eir
wat
er, a
nd (
2) fi
lter
the
ir w
ater
or
mee
t cr
iter
ia fo
r av
oidi
ng fi
ltra
tion
so
that
the
follo
win
g co
ntam
inan
ts a
re c
ontr
olle
d at
the
follo
win
g le
vels
:C
rypt
ospo
ridi
um (
as o
f 1/
1/02
for
syst
ems
serv
ing
>10
,000
and
1/1
4/05
for
syst
ems
serv
ing
<10
,000
) 99
% r
emov
al.
Gia
rdia
lam
blia
: 99
.9%
rem
oval
/inac
tiva
tion
.V
irus
es: 9
9.99
% r
emov
al/in
acti
vati
on.
Leg
ione
lla:
No
limit
, but
USE
PA b
elie
ves
that
if G
iard
ia a
nd v
irus
es a
re r
emov
ed/in
acti
vate
d, L
egio
nella
will
als
o be
con
trol
led.
Tur
bidi
ty: A
t no
tim
e ca
n tu
rbid
ity
(clo
udin
ess
of w
ater
) go
abo
ve 5
nep
helo
met
ric
turb
idit
y un
its
(ntu
); s
yste
ms
that
filt
er m
ust
ensu
re t
hat
the
turb
idit
y go
no
high
er t
han
1 nt
u (0
.5 n
tu f
or c
onve
ntio
nal o
r di
rect
filt
rati
on)
in a
t le
ast
95%
of
the
daily
sam
ples
in a
ny m
onth
. As
of J
an. 1
, 200
2, t
urbi
dity
may
nev
erex
ceed
1 n
tu a
nd m
ust
not
exce
ed 0
.3 n
tu 9
5% o
f da
ily s
ampl
es in
any
mon
th.
HP
C: N
o m
ore
than
500
bac
teri
al c
olon
ies
per
mill
ilite
r.L
ong-
Ter
m 1
Enh
ance
d Su
rfac
e W
ater
Tre
atm
ent
Rul
e (e
ffec
tive
dat
e: J
an. 1
4, 2
005)
; sur
face
wat
er s
yste
ms
or g
roun
dwat
er u
nder
the
dir
ect
infl
uenc
e of
sur
face
wat
er (
GW
UD
I) s
yste
ms
serv
ing
few
er t
han
10,0
00 p
eopl
e m
ust
com
ply
wit
h th
e ap
plic
able
Lon
g-T
erm
1 E
nhan
ced
Surf
ace
Wat
er T
reat
men
t R
ule
prov
i-si
ons
(e.g
., tu
rbid
ity
stan
dard
s, in
divi
dual
filt
er m
onit
orin
g, C
rypt
ospo
ridi
um r
emov
al r
equi
rem
ents
, upd
ated
wat
ersh
ed c
ontr
ol r
equi
rem
ents
for
unfi
lter
edsy
stem
s).
Filt
er B
ackw
ash
Rec
yclin
g: T
he F
ilter
Bac
kwas
h R
ecyc
ling
Rul
e re
quir
es s
yste
ms
that
rec
ycle
to r
etur
n sp
ecifi
c re
cycl
e fl
ows
thro
ugh
all p
roce
sses
of t
he s
yste
m’s
exis
ting
con
vent
iona
l or
dire
ct fi
ltra
tion
sys
tem
or
at a
n al
tern
ate
loca
tion
app
rove
d by
the
sta
te.
**M
ore
than
5.0
% s
ampl
es to
tal c
olifo
rm-p
osit
ive
in a
mon
th. (
For
wat
er s
yste
ms
that
col
lect
few
er th
an 4
0 ro
utin
e sa
mpl
es p
er m
onth
, no
mor
e th
an o
ne s
ampl
e ca
n be
tot
al c
olifo
rm–p
osit
ive
per
mon
th.)
Eve
ry s
ampl
e th
at h
as t
otal
col
iform
mus
t be
ana
lyze
d fo
r ei
ther
fec
al c
olifo
rms
or E
. col
i; if
tw
o co
nsec
utiv
e to
tal c
olifo
rm
sam
ples
are
pos
itiv
e an
d on
e is
als
o po
siti
ve fo
r E
. col
i fec
al c
olifo
rms,
the
sys
tem
has
an
acut
e M
CL
vio
lati
on.
††F
ecal
col
iform
and
E. c
oli a
re b
acte
ria
who
se p
rese
nce
indi
cate
s th
at t
he w
ater
may
be
cont
amin
ated
wit
h hu
man
or
anim
al w
aste
s. D
isea
se-c
ausi
ng m
icro
bes
(pat
hoge
ns)
in t
hese
was
tes
can
caus
e di
arrh
ea, c
ram
ps, n
ause
a, h
eada
ches
, or
othe
r sy
mpt
oms.
The
se p
atho
gens
may
pos
e a
spec
ial h
ealt
h ri
sk fo
r in
fant
s, y
oung
ch
ildre
n, a
nd p
eopl
e w
ith
seve
rely
com
prom
ised
imm
une
syst
ems.
‡‡A
ltho
ugh
ther
e is
no
colle
ctiv
e m
axim
um c
onta
min
ant
leve
l goa
l (M
CL
G)
for
this
con
tam
inan
t gr
oup,
the
re a
re in
divi
dual
MC
LG
s fo
r so
me
of t
he in
divi
dual
co
ntam
inan
ts:
Tri
halo
met
hane
s: b
rom
odic
hlor
omet
hane
(ze
ro);
bro
mof
orm
(ze
ro);
dib
rom
ochl
orom
etha
ne (
0.06
mg/
L).
Chl
orof
orm
is
regu
late
d w
ith
this
gro
up b
ut h
as n
oM
CL
G.
Hal
oace
tic
acid
s: d
ichl
oroa
ceti
c ac
id (z
ero)
; tri
chlo
roac
etic
aci
d (0
.3 m
g/L
). M
onoc
hlor
oace
tic
acid
, bro
moa
ceti
c ac
id, a
nd d
ibro
moa
ceti
c ac
id a
re r
egul
ated
wit
hth
is g
roup
but
hav
e no
MC
LG
s.**
*MC
LG
s w
ere
not
esta
blis
hed
befo
re t
he 1
986
amen
dmen
ts t
o th
e SD
WA
. The
refo
re, t
here
is n
o M
CL
G fo
r th
is c
onta
min
ant.
†††L
ead
and
copp
er a
re r
egul
ated
by
a tr
eatm
ent
tech
niqu
e th
at r
equi
res
syst
ems
to c
ontr
ol t
he c
orro
sive
ness
of
thei
r w
ater
. If
mor
e th
an 1
0% o
f ta
p w
ater
sam
ples
ex
ceed
the
act
ion
leve
l, w
ater
sys
tem
s m
ust
take
add
itio
nal s
teps
. For
cop
per,
the
acti
on le
vel i
s 1.
3 m
g/L
; for
lead
it is
0.0
15 m
g/L
.‡‡
‡Eac
h w
ater
sys
tem
mus
t ce
rtif
y in
wri
ting
to
the
stat
e (u
sing
thi
rd-p
arty
or
man
ufac
ture
r’s
cert
ifica
tion
) th
at w
hen
acry
lam
ide
and
epic
hlor
ohyd
rin
are
used
in
drin
king
wat
er s
yste
ms,
the
com
bina
tion
(or
pro
duct
) of
dos
e an
d m
onom
er le
vel d
oes
not
exce
ed t
he le
vels
spe
cifi
ed, a
s fo
llow
s:A
cryl
amid
e =
0.0
5% d
osed
at
1 m
g/L
(or
equ
ival
ent)
Epi
chlo
rohy
drin
= 0
.01%
dos
ed a
t 20
mg/
L (
or e
quiv
alen
t)
WaterQuality.book Page 16 Friday, April 30, 2010 2:46 PM
PUBLIC WATER SUPPLY REGULATIONS 17
TABL
E 1-
2Re
quire
d sa
mpl
ing
Req
uire
d T
ests
Sam
plin
g L
ocat
ion
Fre
quen
cy: C
omm
unit
y an
d N
ontr
ansi
ent,
Non
com
mun
ity
Syst
ems
Fre
quen
cy: T
rans
ient
, N
onco
mm
unit
y Sy
stem
s
Inor
gani
csE
ntry
poi
nts
to d
istr
ibut
ion
syst
em.
Syst
ems
usin
g su
rfac
e w
ater
: eve
ry y
ear.
Sys
-te
ms
usin
g gr
ound
wat
er o
nly:
eve
ry t
hree
ye
ars.
Nitr
ate:
yea
rly.
Nitr
ite: a
t sta
te o
ptio
n.
Org
anic
s: e
xcep
t tr
ihal
omet
hane
sE
ntry
poi
nts
to d
istr
ibut
ion
syst
em.
Syst
ems
usin
g su
rfac
e w
ater
: eve
ry t
hree
ye
ars.
Sys
tem
s us
ing
grou
ndw
ater
onl
y:
stat
e op
tion
(ca
n be
mod
ifie
d by
the
sta
te
depe
ndin
g on
res
ults
of
prev
ious
tes
ting
an
d sa
nita
ry s
urve
ys).
Stat
e op
tion
.
Org
anic
s:
trih
alom
etha
nes
25%
at
extr
emes
of
dist
ribu
tion
sy
stem
; 75%
at
loca
tion
s re
p-re
sent
ativ
e of
pop
ulat
ion
dist
ribu
tion
.
All
syst
ems
mus
t co
llect
four
sam
ples
per
quar
ter
per
plan
t.*
*Sy
stem
s us
ing
mul
tipl
e w
ells
dra
win
g ra
w w
ater
from
a s
ingl
e aq
uife
r m
ay, w
ith
stat
e ap
prov
al, b
e co
nsid
ered
one
trea
tmen
t pla
nt fo
r de
term
inin
g th
e re
quir
ed n
um-
ber
of s
ampl
es.
Stat
e op
tion
.
Tur
bidi
tyA
t poi
nt(s
) whe
re w
ater
ent
ers
dist
ribu
tion
sys
tem
; all
filte
r ef
flue
nts
if a
sur
face
wat
er
trea
tmen
t pla
nt.
Syst
ems
usin
g su
rfac
e w
ater
: dai
ly. S
ee L
ong
Ter
m 1
Enh
ance
d Su
rfac
e W
ater
Tre
atm
ent
Rul
e fo
r fr
eque
ncy.
Sys
tem
s us
ing
grou
nd-
wat
er o
nly:
sta
te o
ptio
n.
Syst
ems
usin
g su
rfac
e w
ater
or
surf
ace
wat
er a
nd g
roun
dwat
er o
nly:
dai
ly.
Syst
ems u
sing
gro
undw
ater
onl
y: s
tate
op
tion
.
Col
iform
bac
teri
aA
t co
nsum
er’s
fauc
et.
Dep
ends
on
num
ber
of p
eopl
e se
rved
by
wat
er s
yste
m.
Syst
ems
usin
g su
rfac
e w
ater
and
/or
grou
ndw
ater
: one
per
qua
rter
(fo
r ea
ch q
uart
er w
ater
is s
erve
d to
pu
blic
).
Rad
ionu
clid
es:
natu
ral
At
each
ent
ry p
oint
to
the
syst
em.
Qua
rter
ly s
ampl
es u
p to
one
sam
ple
ever
y ni
ne y
ears
for
each
indi
vidu
al c
onta
min
ant
base
d on
pas
t re
sult
s.
Stat
e op
tion
.
Rad
ionu
clid
es:
synt
heti
cA
t en
try
poin
t to
sys
tem
.St
ate
dete
rmin
es w
ho m
ust t
est a
nd w
hen.
Syst
em u
sing
sur
face
wat
er a
nd/o
r gr
ound
wat
er: s
tate
opt
ion.
WaterQuality.book Page 17 Friday, April 30, 2010 2:46 PM
18 WATER QUALITY
Public NotificationPublic water systems that do not comply with the SDWA are required to provide publicnotification. Systems that violate operating, monitoring, or reporting requirements orbriefly exceed an MCL must inform the public of the problem. Even though the problemmay have already been corrected, an explanation must be provided in the news mediadescribing the public health significance of the violation. Some violations are more seriousthan others and three tiers of public notification have been established (Table 1-3). Tier Iviolations are more serious than Tier II and Tier III violations and have more extensivenotification requirements.
The USEPA published new regulations and guidelines in May 2000 for all PWSs to bein compliance with no later than May 6, 2002. These provisions increased the reasons forpublic notifications and shortened the period for the initial notifications for Tier I events(Table 1-3). The USEPA has added wording that the PWS must give notice for all viola-tions of the NPDWR and for other situations determined by the primacy agency. TheUSEPA also stipulates that the users of the water, not just the billed customer, are to benotified. Consecutive systems have to notify their affected customers once they have beennotified by their purchase water supplier. Basically the required notification timetable haschanged to a more uniform, simplified method—that is, Tier I notices must now be given in24 hours, not 72 hours as in the old regulations; Tier II notices are now required in 30 days,not the former 14 days; and Tier III notices are required within one year instead of 90 days.
USEPA provides language mandatory for use with each type of public notification tofully inform the public of the significance of the violation. Notification about tier level andfrequency of violations may vary depending on the state and local regulations, but thepenalty can be no less severe than the federal regulations. Since 9/11, many regulators havegreatly increased their use of the public notification guidelines especially for operatingconditions—for example, overfeed of a treatment chemical such as fluoride—and otherpotential problems in the drinking water. Fluoride now has a requirement for notificationif the secondary MCL of 2.0 mg/L is exceeded generating at least a Tier III notification.Again, check with the local primacy agency as to level of warning.
As has been noted, the USEPA has changed the notification process to include all typesof systems—transient, nontransient, and community water systems—and they must meetthe same time constraints of 24 hours, 30 days, and one year depending on the seriousness ofthe violation and what tier it falls into. Tier I notifications even have the added requirementfor an all-clear notification. The way notifications are to be delivered also varies dependingon the severity of the notice and the type of system. These notifications may include any or amixture of the following as determined by the system emergency notification plan and whatthe primacy agency agrees to in each case: radio, television, newspaper, hand delivery,mobile loudspeakers, texting, publication on system web site, posting in public places,reverse 911, and so on.
WaterQuality.book Page 18 Friday, April 30, 2010 2:46 PM
PUBLIC WATER SUPPLY REGULATIONS 19
TABLE 1-3 Summary of notification requirements
Category of Violation and Causes
TIER I – Immediate notification, within 24 hours (primacy agency will determine follow-up noti-fications including all-clear notices)
• Fecal coliform violations, including failure to sample after initial distribution coliformpositive
• Nitrate, nitrite or total nitrate–nitrite MCL violation, or failure to take confirmationsample
• Chlorine dioxide MRDL, violation in distribution system or failure to take distributionsamples as required
• Exceedance of maximum allowable turbidity level, if elevated to Tier I by primacyagency
• Waterborne disease outbreak or other waterborne emergency
• Special notice for noncommunity water systems (NCWSs) with nitrate exceedancewhere variance has been given by primacy agency
• Other situations or occurrences as determined by the primacy agency
TIER II – Notice as soon as possible but within 30 days (quarterly repeat notifications until the violation is resolved or as directed by primacy agency)
• All MCL, MRDL, and TT violations, except where elevated to Tier I notice as required
• Monitoring violations, if elevated to Tier II by primacy agency
• Failure to comply with variance and exemption conditions
Primacy Agency May Change Any of These to Tier I Classification Based on Potential Threat to Health.
TIER III – Notice within 12 months (repeated annually until resolved)
• Monitoring or testing procedure violations unless elevated to Tier II by primacy agency
• Operation under a variance or exemption
• Special public notices (fluoride secondary maximum contaminant level exceedance,availability of regulatory monitoring results such as the unregulated contaminant mon-itoring results, Long Term 2 Enhanced Surface Water Treatment Rule (Cryptosporidiumor E. coli), D/DBP2 (IDSE),
Derived and adapted from Federal Register 40 CFR Ch. 1 (July 2006 edition) and EPA the Pub-lic Notification Rule: A Quick Reference Guide.
WaterQuality.book Page 19 Friday, April 30, 2010 2:46 PM
20 WATER QUALITY
Formal enforcementIn instances of serious or prolonged noncompliance with federal requirements, SDWA hasprovided USEPA and the states with authority to assess stiff monetary fines.
Monitoring and reporting requirementsTo ensure that drinking water meets federal and state requirements, all water systems arerequired to regularly sample and test the water supplied to consumers. The regulationsspecify minimum sampling frequencies, sampling locations, testing procedures, require-ments for record keeping, and routine reporting to the state. The regulations also coverspecial reporting procedures to be followed if a contaminant exceeds an MCL. Failure tomonitor the water according to regulations, whether intentional or not, can lead to a pub-lic notification incident, the type of notice to be delivered is determined by the type ofcontaminant to be monitored whether the contaminant has acute immediate effects orchronic long term effects. The primacy agency in charge of the drinking water program forthe contaminant will determine the type of violation and the notification procedures.
MonitoringThe federal regulations specify minimum monitoring frequencies, which in many cases area function of the type of water source, the type of treatment, and the size of the water sys-tem. All systems must provide periodic testing for microbiological contamination andanalysis for some chemical contaminants.
With the continual addition of new requirements for further testing of water quality,USEPA has instituted a reorganization of monitoring requirements called the standard-ized monitoring framework.
Reporting and record keepingThe results of all water analyses must be provided periodically to the primacy agency,whether it is federal, state, or local. Failure to have the proper analyses performed or toreport the results to the state primacy agency usually results in the water system having toprovide public notification. Specific information, shown in Table 1-4, must be included onevery laboratory report.
There are also specific requirements for the operation and monitoring records watersystems must keep and for the length of time the records must be retained. These require-ments are summarized in Table 1-5. Although state requirements for monitoring, report-ing, and record retention must be as stringent as federal requirements, they often vary andmay include specific required procedures.
Variances and ExemptionsEach drinking water regulation includes provisions for variances and exemptions. Statesare authorized to grant one or more variances to a water system that cannot comply with
WaterQuality.book Page 20 Friday, April 30, 2010 2:46 PM
PUBLIC WATER SUPPLY REGULATIONS 21
an MCL because of characteristics of the water source(s). A variance may only be grantedto systems that have installed full-scale BAT for treatment of the MCL being violated.Granting of a variance must not result in an unreasonable risk to the public health, andthe state must prescribe a schedule of compliance.
States may exempt a water system from an MCL or treatment technique requirementif it finds that all three of the following conditions exist:
1. The system is unable to comply with the requirement because of compelling factors(which may include economic factors).
2. The exemptions will not result in an unreasonable risk to public health.3. The system was in operation as of January 1, 1989, or, if it was not, no reasonable
alternative source of drinking water is available to the new system.
TABLE 1-4 Laboratory report summary requirements
Type of Information Summary Requirement
Sampling information Date, place, and time of sampling
Name of sample collector
Identification of sample
• Routine or check sample
• Raw or treated water
Analysis information Date of analysis
Laboratory conducting analysis
Name of person responsible
Analytical method used
Analysis results
TABLE 1-5 Record-keeping requirements
Type of Record Time Period
Bacteriological and turbidity analyses 5 years
Chemical analyses 10 years
Actions taken to correct violations 3 years
Sanitary survey reports 10 years
Exemptions 5 years following expiration
WaterQuality.book Page 21 Friday, April 30, 2010 2:46 PM
22 WATER QUALITY
National Secondary Drinking Water RegulationsA National Secondary Drinking Water Regulation is a nonenforceable guideline regard-ing contaminants that may cause aesthetic effects such as taste, odor, and color. Somestates choose to adopt them as enforceable standards. Table 1-6 lists the secondary MCLs.Table 1-7 lists the adverse effects of secondary contaminants.
TABLE 1-6 National Secondary Drinking Water Regulations
Contaminant Secondary Standard
Aluminum 0.05–0.2 mg/L
Chloride 250 mg/L
Color 15 color units
Copper 1.0 mg/L
Corrosivity Noncorrosive
Fluoride 2.0 mg/L
Foaming agents 0.5 mg/L
Iron 0.3 mg/L
Manganese 0.05 mg/L
Odor 3 threshold odor number
pH 6.5–8.5
Silver 0.10 mg/L
Sulfate 250 mg/L
Total dissolved solids 500 mg/L
Zinc 5 mg/L
Note: For more information, read Secondary Drinking Water Regulations: Guidance for Nuisance Chemicals.
WaterQuality.book Page 22 Friday, April 30, 2010 2:46 PM
PUBLIC WATER SUPPLY REGULATIONS 23
CURRENT AND FUTURE RULES AFFECTING DRINKING WATER SYSTEMSExisting rules intended to control microbial risks include the following:
Total Coliform Rule (TCR)Unregulated Contaminant Monitoring Rule (UCMR)
TABLE 1-7 Adverse effects of secondary contaminants
Contaminant Adverse Effect
Chloride Causes taste. Adds to total dissolved solids and scale. Indicates contamination. Can accelerate the corrosion of some metals.
Color Indicates dissolved organics may be present, which may lead to trihalomethane formation. Unappealing appearance.
Copper Undesirable metallic taste.
Corrosivity Corrosion products unappealing to consumers. Causes tastes and odors. Corrosion products can affect health. Corrosion causes costly
deterioration of water system.
Fluoride Dental fluorosis (mottling or discoloration of teeth).
Foaming agents Unappealing appearance. Indicates possible contamination.
Hydrogen sulfide Offensive odor. Causes black stains on contact with iron. Can accu-mulate to deadly concentration in poorly ventilated areas. Flammable
and explosive.
Iron Discolors laundry brown. Changes taste of water, tea, coffee, and other beverages.
Manganese Discolors laundry. Changes taste of water, tea, coffee, and other beverages.
Odor Unappealing to drink. May indicate contamination.
pH Below 6.5, water is corrosive. Above 8.5, water will form scale, taste bitter.
Sulfate Has a laxative effect.
Total dissolved solids Associated with taste, scale, corrosion, and hardness.
Zinc Undesirable taste. Milky appearance.
WaterQuality.book Page 23 Friday, April 30, 2010 2:46 PM
24 WATER QUALITY
Surface Water Treatment Rule (SWTR)Long Term 1 Enhanced Surface Water Treatment Rule (LT1ESWTR)Long Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR)Filter Backwash Recycling Rule (FBRR)Ground Water Rule (GWR)
Existing rules intended to control chemical risks include the following:
ArsenicNational Interim Primary Drinking Water Regulations (NIPDWRs)Fluoride Rule (FR)Volatile Organic Chemicals (Phase I) (VOCs)Lead and Copper Rule (LCR)Synthetic Organic Chemicals and Inorganic Chemicals (Phase II) (SOCs and IOCs)Stage 1 Disinfectants Disinfection By-Products Rule (D/DBPR) Stage 2 Disinfectants Disinfection By-Products (D/DBP2)Radionuclides RuleConsumer Confidence Report (CCR) RulePublic Notification (PN) RuleUnregulated Contaminant Monitoring Rule (UCMR)
A future rule intended to control microbial risks is:
Total Coliform Rule (revised)
Future regulatory actions intended to control chemical risks include the following:
Radon in Drinking Water RuleContaminant Candidate List (CCL)
Total Coliform RuleThe Total Coliform Rule (TCR) (published June 29, 1989/effective December 31, 1990) setboth health goals (MCLGs) and legal limits (MCLs) for total coliform levels in drinking water.The rule also details the type and frequency of testing that water systems must perform.
The coliforms are a broad class of bacteria that live in the digestive tracts of humansand many animals. The presence of coliform bacteria in tap water suggests that the treat-ment process is not working properly or that there is a problem in the pipes. Among thehealth problems that contamination can cause are diarrhea, cramps, nausea, and vomit-
WaterQuality.book Page 24 Friday, April 30, 2010 2:46 PM
PUBLIC WATER SUPPLY REGULATIONS 25
ing. Together these symptoms comprise a general category known as gastroenteritis. Gas-troenteritis is not usually serious for a healthy person; however, it can lead to moreserious problems for people with weakened immune systems, such as the very young,elderly, or immunocompromised.
In the rule, USEPA set the health goal for total coliforms at zero. Because there havebeen waterborne-disease outbreaks in which researchers have found very low levels of coli-forms, any level indicates the potential for some health risk.
USEPA also set a legal limit on total coliforms. Systems collecting 40 or more sam-ples per month must not find coliforms in more than 5 percent of the samples they takeeach month to meet USEPA’s standards. If more than 5 percent of the samples containcoliforms, water system operators must report this violation to the state and the public.Systems that collect fewer than 40 samples per month are allowed only one positive coli-form sample per given month. More than one coliform-positive sample for these systemsis considered a monthly MCL violation.
When a system finds coliforms in drinking water, it may indicate that the treatmentsystem is not performing properly. To avoid or eliminate microbial contamination, sys-tems may need to take several actions, including repairing the disinfection/filtration equip-ment, flushing or upgrading the distribution system, and enacting source water protectionprograms to prevent contamination.
If a sample tests positive for coliforms, the system must collect a set of repeat sampleswithin 24 hours. When a routine or repeat sample tests positive for total coliforms, it mustalso be analyzed for fecal coliforms and Escherichia coli (E. coli), which are coliformsdirectly associated with fresh feces. A positive result to this last test signifies an acuteMCL violation, which necessitates rapid state and public notification because it representsa direct health risk.
The number of coliform samples a system must take depends on the number of cus-tomers it serves. Systems that serve fewer than 1,000 people may test once a month or lessfrequently. Systems with 50,001 to 59,000 customers must test 60 times per month, andthose with 2,270,001 to 3,020,000 customers must test at least 420 times per month.[NOTE: for a complete chart based on population (see Table 4-2 in chapter 4)] These areminimum schedules, and many systems test more frequently.
Revisions to the TCR are under discussion as of the publication of this book but notofficially proposed. The revisions will likely emphasize a more proactive approach thatrequires utilities to ensure barriers to microbial contamination are in place and are effec-tive. They will emphasize operation and maintenance of the distribution system compo-nents. USEPA has called for distribution system research and information collection tosupport this approach. The emphasis of the revised rule is a shift from monitoring resultsthat trigger public notification to monitoring results that prompt an assessment and cor-rective action. The new rule may be proposed in 2010.
The Ground Water Rule took effect in December 2009. It links to the TCR in that posi-tive coliform samples in the distribution system of a CWS with groundwater supply or a
26 WATER QUALITY
consecutive system to a CWS with groundwater supply may trigger microbial sampling of thegroundwater sources along with the distribution samples. (See Ground Water Rule section.)
Unregulated Contaminant Monitoring RuleThe SDWA requires the USEPA to create a list of contaminants that should be monitoredin water systems. These are contaminants that have the probability of being present in thefinished water supply and may have an adverse effect on human health or the environ-ment. The 1996 amendments to SDWA require USEPA to establish criteria for a monitor-ing program for unregulated contaminants and to publish a list of contaminantspotentially present in water to be monitored as part of this program. USEPA has revisedand will continue to revise the Unregulated Contaminant Monitoring Rule (UCMR) asdata become available about newly discovered potential sources of contamination or asmethodology becomes available to test for various potentially harmful contaminants. Thedata generated by the new UCMR list will be used to evaluate and prioritize contaminantson the Drinking Water Contaminant Candidate List (DWCCL), a list of contaminantsUSEPA is considering for possible new drinking water standards. These data will help toensure that the USEPA has the sound scientific data it needs to make decisions aboutfuture drinking water standards.
The new rule includes
• A new list of contaminants for which public water systems must monitor;• Analytical methods for some of these contaminants;• Requirements that all large public water systems (PWSs), and a representative sample
of small PWSs, monitor for listed contaminants for which methods have beenpromulgated;
• Requirements to submit the monitoring data to USEPA and the states for inclusion inthe National Drinking Water Contaminant Occurrence Database;
• Requirements to notify consumers of the results of monitoring.
USEPA revised the UCMR (List 1) on September 17, 1999. List 2 was published Feb-ruary 24, 2005, and revisions to List 2 were published August 22, 2005.
Surface Water Treatment RuleThe Surface Water Treatment Rule (published June 29, 1989/effective December 31, 1990)seeks to prevent waterborne diseases caused by viruses, Legionella, and Giardia lamblia.These disease-causing microbes are present at varying concentrations in most surfacewaters. The rule requires that water systems filter and disinfect water from surface watersources to reduce the occurrence of unsafe levels of these microbes.
The rule applies to the operation of every public water system that uses surface wateras a source. It also imposes new requirements on water systems that use groundwater that
WaterQuality.book Page 26 Friday, April 30, 2010 2:46 PM
PUBLIC WATER SUPPLY REGULATIONS 27
might become contaminated by surface water; these systems are termed groundwaterunder the direct influence of surface water, usually abbreviated GWUDI.
As the name suggests, this rule governs water supplies whose source of drinking wateris surface water, which it defines as “all water open to the atmosphere and subject to sur-face runoff.” This water, which most of the country’s large water systems use, is in rivers,lakes, and reservoirs. Surface water is particularly susceptible to microbial contaminationfrom sewage treatment plant discharges and runoff from stormwater and snowmelt. Thesesources often contain high levels of fecal microbes that originated in livestock wastes orseptic systems.
The purpose of the regulation is to protect the public from waterborne disease. Theorganisms that cause the waterborne diseases most frequently diagnosed in the UnitedStates are Giardia lamblia, Cryptosporidium, Legionella, viruses, and some types of bacte-ria. No simple, inexpensive tests are available for detecting the presence of Cryptosporid-ium, Giardia, and Legionella. Current methods for determining coliform are only a generalindicator of fecal contamination, not really a true indicator of the presence of the othertypes of organisms.
Because of this inability to test routinely for the presence of specific microorganisms,USEPA has required all surface water systems to use a treatment technique that ensuresthe finished water will meet the water quality goals without the need for specific testing.Studies indicate that Cryptosporidium oocysts, Giardia cysts, and viruses are among themost resistant waterborne pathogens. Surface water systems must therefore use filtrationand disinfection processes that either removes or inactivates virtually all of these microor-ganisms. Treatment must assure the removal or inactivation of 99.9 percent (3 logs) ofGiardia cysts and 99.99 percent (4 logs) of viruses.
All systems must filter and disinfect their water to provide a minimum of 99.9 percentcombined removal and inactivation of Giardia and 99.99 percent of viruses. The adequacy ofthe filtration process is established by measuring turbidity (a measure of the concentrationof particles) in the treated water and determining if it meets USEPA’s performance standard.Some public water systems that have pristine sources may be granted a waiver from the fil-tration requirement. These systems must provide the same level of treatment as those thatfilter; however, their treatment is provided through disinfection alone. The great majority ofwater suppliers in the United States that use a surface water source filter their water.
To ensure adequate microbial protection in the distribution system, water systems arealso required to provide continuous disinfection of the drinking water entering the distri-bution system and to maintain a detectable disinfectant level within the distribution sys-tem. The distribution system is a series of pipes that delivers treated water from the watertreatment plant to the consumer’s tap.
Ingestion of Cryptosporidium, Giardia, and viruses can cause problems in the humandigestive system, generally in the form of diarrhea, cramps, and nausea. Legionella bacteriain water are only a health risk if the bacteria are aerosolized (e.g., in an air-conditioningsystem or a shower) and then inhaled. Inhalation can result in a type of pneumonia knownas Legionnaires’ disease.
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28 WATER QUALITY
The rule sets nonenforceable health goals, or MCLGs, for Legionella, Giardia, Cryp-tosporidium, and viruses at zero because any amount of exposure to these contaminantsrepresents some health risk.
C × T valuesThe SWTR treatment technique goals may be partially met by using disinfection treatment.The effectiveness of a disinfectant in inactivating Giardia cysts and viruses depends on
• Type of disinfectant used,• Residual concentration of the disinfectant,• Period of time the water is in contact with the disinfectant,• Water temperature,• Chlorine used, and• pH of the water.
USEPA has determined that a combination of the residual concentration C of a disin-fectant (in milligrams per liter) multiplied by the contact time T (in minutes) can be usedas a measure of the disinfectant’s effectiveness in killing or inactivating microorganisms.In other words, a water system can use a relatively small application of disinfectant andkeep it in contact with the water for a long time or use a large disinfectant dose in contactwith the water for a short time and obtain approximately the same results.
All surface water systems without filtration treatment are required to compute theC × T value for their treatment process daily, and the value must always be above theminimum value specified by USEPA. The allowable levels vary by both the type(s) ofdisinfectant used and the water temperature. Systems using filtration treatment mustcalculate and meet the C × T values specified by the state primacy agency.
Filtration treatmentMost surface water systems and systems designated by the state as GWUDI must provideboth disinfection and filtration treatment to meet the treatment technique requirements.The current technologies specified by the SWTR are conventional treatment, direct filtra-tion, slow sand filtration, diatomaceous earth filtration, reverse osmosis, and alternatetechnologies including other membrane technologies and ultraviolet (UV). These pro-cesses are covered in detail in another book in this series, Water Treatment.
Some surface water systems that are using especially clean and protected water sourcescan avoid the requirement to provide filtration and may use disinfection treatment only.However, these systems must meet many additional requirements for providing sourcewater protection and for monitoring water quality and the operation of their system.
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Other SWTR requirementsSome of the other principal requirements of the SWTR are as follows:
• For most systems, the turbidity of water entering the distribution system must beequal to or less than 0.5 ntu in at least 95 percent of the measurements taken eachmonth. At no time may the turbidity exceed 1 ntu.
• The disinfection residual of water entering the distribution system must generally bemonitored continuously for systems serving a population of more than 3,300. Theresidual cannot be less than 0.2 mg/L for more than 4 hours during periods whenwater is being served to the public. Any time the residual falls below this level, thesystem must notify the state.
• The disinfectant residual must be measured at the same points on the distributionsystem that are used for coliform sampling. Disinfectant residuals must not be unde-tectable in more than 5 percent of the samples each month for any two consecutivemonths that water is served to the public.
• Systems must submit special reports to the state detailing the monitoring required bythe SWTR.
Long-Term 1 Enhanced Surface Water Treatment RuleThe Long-Term 1 Enhanced Surface Water Treatment Rule (LT1ESWTR) applies to sur-face water (and GWUDI) systems serving fewer than 10,000 people. LT1ESWTR is basedon the requirements for systems serving more than 10,000 people that are contained in theInterim Enhanced Surface Water Treatment Rule (IESWTR).
LT1ESWTR includes the following requirements:
1. Systems are required to achieve a 2-log removal (99 percent) of Cryptosporidium.2. Systems get credit for 2-log removal of Cryptosporidium by meeting a lower turbidity
(combined filter effluent) performance standard of 0.3 ntu in 95 percent of monthlymeasurements, never to exceed 1 ntu (for systems using conventional or directfiltration).
3. Systems must monitor effluent that passes through each individual filter, and basedon turbidity levels they may be required to perform follow-up activities.
4. Systems may be required by the state to compile a disinfection profile based on thelevels of DBPs in their system (80 percent of the Stage 1 MCLs is the criteria).
5. Systems looking to make a significant change in their disinfection practice need todetermine the disinfection benchmark and present that in discussions with state pri-macy agencies.
6. New finished-water reservoirs must be covered.
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The turbidity levels of water leaving the treatment plant were lowered to 0.3 ntu with amaximum level of 1.0 ntu. For the individual filters, the turbidity must not exceed 0.3 ntufor two consecutive 15-minute periods, nor can it exceed 0.5 ntu at the 4-hour and 4-hour-and-15-minute mark after being returned to service for any reason.
Long-Term 2 Enhanced Surface Water Treatment Rule The Long-Term 2 Enhanced Surface Water Treatment Rule was published January 5, 2006,and became effective July 1, 2006, for large systems. The LT2ESWTR adds to the SurfaceWater Treatment Rule in that it adds testing for pathogens Cryptosporidium and/or E. Colialong with turbidity in the source waters for a two-year period, depending on system size.Small systems tested for E. Coli only because of the expense of testing for Cryptosporidium.The testing for Cryptosporidium and E. Coli was to be completed by each system over atime frame based on system size to determine if current treatment practices and equipmentin place would reliably remove these organisms. After the testing is completed calculationsare made to determine the “bin” a system falls into (bins are average concentrations in thesource water for the theoretical potential for contamination). The utility would then berequired to upgrade the treatment or improve source water protection if needed in a certaintime frame. The regulation calls for periodic follow-up of sampling programs to check thatthe potential for contamination did not become more severe in the interim, i.e., that thesource bin changed.
This additional protection could be determined by using suggested methods from the“toolbox” including periodic monitoring, improvements to the treatment techniquesincluding additional disinfectants such as UV and source water protection.
The regulation also called for continuous monitoring at the entry point to the distri-bution system with a minimum of 0.2 mg/L of chlorine residual.
Radionuclides RuleThis rule, promulgated December 7, 2000, retained the existing MCLs for combined radium226 and 228 of 5 pCi/L, the gross alpha limit of 15 pCi/L, and gross beta/photon emitters of4 mrem/year. This rule also added for the first time an MCL for uranium of 30 microgramsper liter (μg/L). This rule is unique in that the results and sampling regime the utility mustcomply with are based on the varying level of results (average annual quarterly) for eachcontaminant at each sample site. There are also many variations, exemptions, and condi-tions that can affect the sampling program and determine whether the system is in violationor not. A full reading of the rule and consultation with your primacy agency will provide youwith the guidance needed to comply. Your primacy agency will also guide you in the properway to report the results in your consumer confidence report (CCR) since the possiblereporting span can be quarterly, annually, or up to every nine years.
Quarterly sampling for individual regulated radionuclides at the individual entrypoints to the system began on December 8, 2003, but any grandfathered data that met the
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sampling and testing criteria from June 2000 through December 8, 2003, were eligible foruse, except data for beta/photon emitters. The first four quarters of samples determinedthe frequency for future required testing for each of the individual radionuclides.
Further information on the regulation and two tables are located in Chapter 8.
Filter Backwash Recycling RuleThe Filter Backwash Recycling Rule (FBRR) published in June 2001 is intended to reducethe opportunity for recycle practices to adversely affect the performance of drinking watertreatment plants and to help prevent microbes such as Cryptosporidium from passingthrough treatment systems and into finished drinking water. Customers may become ill ifthey drink such contaminated water.
Spent filter backwash water, thickener supernatant, and liquids from dewatering pro-cesses can contain microbial contaminants, often in very high concentrations. Recyclingthese streams can reintroduce microbes and other contaminants to the treatment system.Additionally, large volumes of recycle streams may upset treatment processes, allowingcontaminants to pass through the system. To minimize these risks, the FBRR requiresthat recycle streams pass through all the processes of a system’s existing conventional ordirect filtration system (as defined in 40 CFR 141.2) that USEPA has recognized as capa-ble of achieving 2-log (99 percent) Cryptosporidium removal. The FBRR also allows recy-cle streams to be reintroduced at an alternate location, if the location is state approved.
For systems covered under this rule, the state had to be notified by December 8, 2003,of the intent to continue recycling the process streams just listed. The state would reviewand approve a plant for the operating capacity of the recycling plan. By June 2006 allplants that were recycling had to complete any capital work and be in compliance with theapproved state plan as to recycle return location in the treatment stream and the volumesof recycled water based on plant flow and capacity.
Lead and Copper RuleThe Lead and Copper Rule is substantially different from the rest of this cluster of rules.The other rules require water systems to treat water so that when it leaves their facilities, itis clean and safe to drink. This rule (published June 7, 1991/effective December 7, 1992)regulates two contaminants that, when present in the distribution system or in consumers’plumbing, can taint the drinking water after it leaves the treatment plant.
Lead and copper are both naturally occurring metals. Both have been used to makehousehold plumbing fixtures and pipes for many years, though Congress banned the useof lead solder, pipes, and fittings in 1986. The two contaminants enter drinking waterwhen water reacts with the metals in the pipes. This is likely to happen when water, “theuniversal solvent,” sits in a pipe for more than a few hours.
Lead and copper have different health effects. Lead is particularly dangerous to fetusesand young children because it can slow their neurological and physical development.
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Anemia may be one sign of a child’s exposure to high lead levels. Lead may also affect thekidneys, brain, nervous system, and red blood cells. It is considered a possible cause of can-cer. Copper is a health concern for several reasons. At very low levels, it is necessary to thebody; in the short term, however, consumption of drinking water containing copper wellabove the action level could cause nausea, vomiting, and diarrhea. It can also lead to seri-ous health problems in people who have Wilson’s disease. Exposure over many years todrinking water containing copper above the action level could increase the risk of liver andkidney damage. To prevent these effects, USEPA set health goals (MCLGs) and action lev-els for lead and copper.
USEPA required water systems to evaluate not only the pipes in their distribution sys-tems but also the ages and types of housing that they serve. This evaluation causes thewater system to sample the water in which the probability of contamination is greatest.Based on this information, the systems must collect water samples at points throughoutthe distribution system that are vulnerable to lead contamination, including regularly usedbathroom or kitchen taps.
When the level of lead or copper in 10 percent of the tap water samples reaches theaction level or 90th percentile, the water system must begin certain water treatment steps.An action level is different from an MCL in that while an MCL is a legal limit on a con-taminant, an action level is a trigger for additional prevention or removal steps plus addi-tional testing. The Lead and Copper Rule is different from the others in that it deals witha calculated percentile level to determine compliance.
The rule requires water systems to apply certain treatment techniques for high lead orcopper levels. At a minimum, systems must maintain optimal corrosion control. Corro-sion control does not reduce the contaminant level but helps prevent the water from beingcontaminated in the first place. By increasing the water’s pH or hardness, water systemscan make their water less corrosive and therefore less likely to corrode the pipes andabsorb the lead or copper. Consumers can further reduce the potential for elevated leadlevels at the tap by ensuring that all plumbing and fixtures meet local plumbing codes.
When a water system exceeds the 90th percentile of either action level for lead or copper,it must also assess its source water. In most cases, there will be little or none of either con-taminant in the source water, and no treatment will be necessary. When there are high levelsin the source water, treatment of that water, in conjunction with corrosion control, furtherlessens the chance that consumers will have elevated levels of lead and copper at the tap.
The rule also requires systems that exceed the 90th percentile lead action level to edu-cate the affected public about reducing their lead intake.
There are other sections of the Lead and Copper Rule (LCR) to follow.
Optimal Corrosion ControlLarge utilities must conduct corrosion control studies unless they can demonstrate thattheir corrosion control is already optimal. Utilities have attained optimal corrosion control
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if the difference between the source water lead concentration and the 90th percentile fromthe tap samples is less than 0.005 mg/L.
Small and medium-size utilities are deemed to have optimal corrosion control if theymeet the lead and copper action levels for two consecutive sampling periods. How to con-duct corrosion control studies is outlined in references listed in the Selected Supplemen-tary Readings at the end of this chapter.
Water Quality ParametersAll large water systems, as well as all medium-size and small water systems that exceed theaction levels, are required to monitor for additional contaminants. This practice will helpdetermine if the systems are maintaining optimal corrosion control. These parameters areanalyzed as follows:
• Conductivity may be measured in the field or the sample returned to the laboratoryfor measurement.
• The pH must be measured in the field, and only the probe method is approved byUSEPA.
• Temperature must be measured in the field along with pH and may be measured witha handheld thermometer or with a combined temperature–pH electrode.
• Calcium must be measured in the laboratory. Because the sample for calcium must beacidified for analysis, a separate sample for calcium must be collected.
• Alkalinity must be measured in the laboratory.• If a phosphate-based corrosion inhibitor is used, an orthophosphate analysis must be
conducted.• If a silica-based corrosion inhibitor is used, a silica analysis must be conducted.
Samples for the water quality parameters may be collected at the usual bacterial sam-ple points in the distribution system. Either glass or plastic containers may be used unlesssilica is being measured, in which case plastic is required. Samples should be collectedfrom fully flushed sample taps, and the representativeness of the sample site for producingthe desired data must be considered.
Results of these analyses are reviewed by the primacy agency, which will then establishthe ranges of the parameters within which the utility may operate.
DRINKING WATER PROGRAM REQUIREMENTS
Reporting and Record KeepingThe results of all water analyses must be provided periodically to the state. Failure to havethe proper analyses performed or to report the results to the state primacy agency usually
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results in the water system having to provide public notification. Specific informationshown in Table 1-4 must be included on every laboratory report.
There are also specific requirements for the records that must be kept by water sys-tems on their operation and monitoring and for the length of time the records must beretained. These requirements are summarized in Table 1-5. Although state requirementsfor monitoring, reporting, and record retention must be as stringent as the federal require-ments, they often vary and may include specific procedures that must be used.
SPECIAL REGULATION REQUIREMENTSIn addition to the initial programs required by the SDWA, USEPA has drafted severalspecific rules to address various types of water-contaminant problems. Some of these ruleshave been promulgated, and others are still under development. Several of the moreimportant rules are described in the following sections.
Arsenic RuleAs of January 23, 2003, the USEPA revised the drinking water standard for arsenic from50 μg/L to 10 μg/L. This revision was enacted to provide additional protection for 13 mil-lion Americans against an increased risk of cancer and other health problems includingcardiovascular disease, diabetes, and neurological effects. USEPA is continuing to reviewthe new standard for arsenic in drinking water. It will work with the National Academy ofSciences and the National Drinking Water Advisory Council to reassess the scientific andcost issues associated with the rule and determine if any further changes will be needed.The rule also reset the testing cycle for many systems since some of the older data sampleresults had detection limits above the new MCL of 10 μg/L. Some of these sample routinesare now out of sequence with the normal sampling dates for inorganic chemicals estab-lished under the Inorganic Chemicals regulations.
Stage 1 Disinfectants Disinfection By-Products Rule(Stage 1 D/DBPR)Disinfection by-products are formed when organic materials, naturally present in sourcewaters, combine with a disinfectant. Common organics present in many surface watersources are humic acids. Disinfectants commonly used in drinking water treatment includechlorine, chloramines, ozone, and chlorine dioxide. Both the amount and the types of DBPsformed depend on many factors, including the amount and types of organic precursors ini-tially present, pH, time of exposure to disinfectant, temperature, and type of disinfectant.
The Stage 1 Disinfectants Disinfection By-Products (D/DBP) Rule applies to both sur-face water and groundwater systems and has far-reaching effects for US water utilities.Unlike the existing total trihalomethane (TTHM) regulation that only applies to systemsserving more than 10,000 people, the D/DBP Rule applies to all systems regardless of the
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size of the population served. Stage 1 of the rule lowers the allowable TTHM levels from100 μg/L to 80 μg/L. In addition, it regulates haloacetic acids (HAA5) at 60 μg/L chlorite at1.0 mg/L, and bromate at 0.010 mg/L. The rule sets maximum residual disinfectant levels forchlorine (4 mg/L as Cl2), chloramines (4.0 mg/L as Cl2), and chlorine dioxide (0.8 mg/L asClO2). The rule also includes a treatment requirement for enhanced coagulation for surfacewater sources where conventional treatment is applied. The timeline for compliance rangesfrom 18 months for surface water systems serving 10,000 or more people to 60 months forgroundwater systems serving fewer than 10,000 persons.
The MCL for TTHMs (100 μg/L) has been lowered in the final Stage 1 D/DBP, promul-gated in December 1998. The removal of total organic carbon (TOC) to reduce the formationof DBPs is achieved by the treatment technique of enhanced coagulation or enhanced soften-ing that specifies the percentage of influent TOC that must be removed based on the rawwater TOC and alkalinity levels (see Regulations).
Stage 2 Disinfectants/Disinfection By-Products RuleThe Stage 2 D/DBP Rule will apply to all community and nontransient, noncommunitywater systems that add a disinfectant other than UV or deliver water that has been disin-fected. Compliance will be based on Locational Running Annual Average (LRAA—running annual average at each sample location). Implementation of this rule will bestaged. Three years after promulgation, all systems must comply with the Stage 1 D/DBPRule MCL (80/60 μg/L LRAA) and 120/100 μg/L THM/HAA5 LRAA. Six years afterpromulgation, large and medium-size systems (population served ≥10,000) must complywith 80/60 μg/L LRAA based on new sampling sites identified by lifetime distribution sys-tem evaluation (LDSE). Small systems must comply with 80/60 μg/L LRAA based onnew sampling sites identified through the IDSE and routine DBP 1 sampling programsby 10 years after promulgation. The final rule was June 2003; effective date was in June 2006.
Ground Water Rule (GWR)The GWR applies to all public water supplies that use groundwater, regardless of systemsize or type and whether it is a community or noncommunity system. This rule was pub-lished in November 2006. The effective date for all groundwater systems was December1, 2009, to conduct compliance monitoring for coliform and/or meet the 4-log virus inac-tivation or removal or state-approved combination of techniques. Under this rule, pri-macy agencies must complete a sanitary survey by December 31, 2012, for allgroundwater systems that do not meet the performance criteria and by December 31,2014, for all that do. The survey must identify any significant deficiencies that could causecontamination of the water used by consumers. A hydrogeologic sensitivity assessmentmust also be completed to determine the susceptibility of the groundwater source to con-tamination. Microbial monitoring will be required for systems that do not disinfect, thatdraw from a susceptible source, or that detect fecal indicators during routine monitoring.
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For systems that disinfect, have any uncorrected significant deficiencies, or draw from asusceptible source, 4-log inactivation of viruses must be demonstrated by providing ade-quate C × T.
The rule stipulates the type and frequency of disinfectant residual monitoringdepending on system size, with larger systems requiring continuous monitoring andsmaller systems resorting to daily monitoring. The rule also relates positive samples in thedistribution system used for compliance with the TCR to requirements for source watermonitoring including consecutive system monitoring.
Consumer Confidence Report RulePromulgated in 1998, the Consumer Confidence Report Rule (CCR Rule) was put in placeto provide the public with enough information concerning the sources and quality of theirwater supply to allow them to make an informed decision about the health effects of waterthey were consuming. The report had to contain eight informational groups:
1. Water system information (contact person at the utility; what the public can do to bepart of the process)
2. Sources of water for the system by type and name if appropriate3. Definitions for the layperson of the key elements in the report, including maximum
contaminant level (MCL), maximum contaminant level goal (MCLG), maximum dis-infectant residual level (MRDL), maximum disinfectant residual level goal (MRDLG),action level (AL), treatment technique (TT), minimum detection limit (MDL) for atest, and any other pertinent classifications that might need defining
4. A table listing the detected contaminants and detection limits (MCL, MCLG, TT,etc.) plus specific health-effects language and known sources of contamination
5. Information on other nonregulated contaminants if detected (e.g., radon, Cryptospo-ridium, Giardia)
6. Compliance record listing any violations or special notices for any of the regulations7. Listing of any variances or exemptions (if applicable) and description of the reason
for noncompliance8. Required educational information about contaminants such as lead, arsenic, nitrate/
nitrite, and Cryptosporidium, and vulnerable populations
The water supplier is also allowed to add data describing the types of treatment theutility uses and what is being done to safeguard the water sources and water supply. Theutility may also include public relations information about costs of treatment and anyplans that may be in place to improve the plants and system to provide a safe supply.
This is the timetable associated with the gathering and dissemination of informationfrom the previous calendar year with regard to this rule:
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• April 1: The CWS must supply the necessary information in the previous list to anyother CWS it sells treated water to.
• July 1: The CWS must have distributed a copy of the CCR to customers and to localand state primacy agencies.
• October 1 (or 90 days after the distribution of the CCR): The CWS must supply an“Annual Proof of Distribution” certification to the local and state primacy agencies.
• A CWS serving 100,000 or more persons must post its CCR on a publicly accessibleweb site—its own or one designated by the primacy agency, or both.
• The CWS must make a copy of the CCR available to any interested party whorequests one, whether a customer or not.
It is recommended that you check with the agency having primacy for the drinkingwater in your area to ensure that any nuances are being met such as language criteria, dis-tribution requirements, reporting requirements, and any other special circumstances orchanges in local rules or regulations that may have occurred since the last distribution.Again, these vary by state and locality.
Proposed Radon in Drinking Water RuleThe Proposed Radon in Drinking Water Rule applies to all community water systems thatuse groundwater or mix groundwater and surface water. The proposed MCL is 300 pCi/Lat the point of entry from each source of supply. An alternative MCL of 4,000 pCi/Lwould be allowable if the CWS or state develops a multimedia mitigation (MMM or“3M”) program for radon. This rule was proposed in November 1999, and the final rulewas originally expected to be promulgated by late 2009. A revised possible effective datewould be late in 2013. At this writing, there has been no movement on this rule.
Online ResourcesThe USEPA web site has the latest updates on regulatory issues. State health departmentweb sites have the latest state regulatory information. See Table 1-8 for a partial list ofresources.
The Federal Register is available on the Internet and in most libraries. The FederalRegister publishes the entire USEPA document for each rule or act and provides thedetailed information necessary to understand it.
If you do not have access to the Internet, a public or university library will have accessto the Internet or to the Federal Register. For a synopsis of the proposed rules and regula-tions and insight into upcoming legislation, consult the Journal of the American WaterWorks Association and the Water Quality Association.
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TABLE 1-8 Partial list of Internet resources
Resource Internet Site
Water Quality Association http://wqa.org
Federal Register www.archives.gov/federal_register
Arsenic Rule www.epa.gov/safewater/arsenic.html
Contaminant Candidate List (CCL) www.epa.gov/safewater/ccl/cclfs.html
Consumer Confidence Report Rule www.epa.gov/safewater/ccr1.html
Cross-Media Electronic Reporting Regulation (CROMERR)
www.epa.gov/cdx/cromerrr/propose/index.html
Filter Backwash Recycling Rule www.epa.gov/safewater/filterbackwash.html
Ground Water Rule www.epa.gov/safewater/gwr.html
Interim ESWT Rule www.epa.gov/safewater/mdbp/ieswtr.html
Long Term 1 ESWT Rule www.epa.gov/safewater/mdbp/lt1eswtr.html
Long Term 2 ESWT Rule www.epa.gov/safewater/mdbp/mdbp.html#it2
MTBE www.epa.gov/safewater/mtbe.html
Public Notification Rule www.epa.gov/safewater/pn.html
Radionuclides Rule www.epa.gov/safewater/standard/pp/radnucpp/html
Radon Rule www.epa.gov/safewater/radon.html
Six-Year Review www.epa.gov/safewater/review.html
Stage 1 D/DBP Rule www.epa.gov/safewater/mdbp/dbp1.html
Total Coliform Rule www.epa.gov/safewater/disinfection/tcr/
Stage 2 D/DBP Rule www.epa.gov/safewater/mdbp/mdbp.html#it2
UCM Rule www.epa.gov/safewater/standard/ucmr/main.html
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SELECTED SUPPLEMENTARY READINGSBloetscher, F. 2009. Water Basics for Decision Makers. Denver, CO: American Water
Works Association.
Drinking Water Regulations and Health. 2003. Hoboken, NJ.: Wiley-Interscience(available from AWWA).
FACTOIDS: Drinking Water and Ground Water Statistics for 2008. 2008. WashingtonD.C.: US Environmental Protection Agency.
Federal Register 40 CFR Ch. 1 and EPA the Public Notification Rule: A Quick ReferenceGuide. 2006. Washington D.C.: US Environmental Protection Agency.
Handbook of CCL Microbes in Drinking Water. 2002. Denver, CO: American WaterWorks Association.
Pizzi, N.G. 2006. Filter Operations Field Guide. Denver, CO: American Water WorksAssociation.
Pizzi, N.G. 2007. Pretreatment Field Guide. Denver, CO: American Water WorksAssociation.
Scharfenaker, M., J. Stubbart, and W.C. Lauer. Field Guide to SDWA Regulations. 2006.Denver, CO: American Water Works Association.
Stubbart, J., W.C. Lauer, and T.J. McCandless. 2004. AWWA Guide Water OperatorField Guide. Denver, CO: American Water Works Association.
USEPA. 1992. Secondary Drinking Water Regulations: Guidance for Nuisance Chemicals.Washington D.C.: US Environmental Protection Agency.
Water Quality and Treatment. 6th ed. 2010. New York: McGraw-Hill and AmericanWater Works Association (available from AWWA).
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C H A P T E R 2
Water Quality Monitoring
All public water systems monitor water quality to some extent. Small systems with consis-tently good-quality water from deep wells may only need to provide occasional monitoring.Because surface water is more prone to variations in water quality, systems using surface-water sources are required to monitor their water on a more frequent or continuous basisthan systems using groundwater.
Water quality is monitored to meet federal, state, and local requirements and for pro-cess control.
The contaminants that are monitored under US Environmental Protection Agency(USEPA) requirements are extensive, and public water systems must monitor water qual-ity to ensure proper and economic treatment as well as to comply with regulations.
SAMPLING
Importance of SamplingSampling is a vital part of monitoring the quality of water in a water treatment process,distribution system, and supply source. However, errors occur easily when recording waterquality information. Every precaution must be taken to ensure that the sample collected isas representative as is feasible of the water source or process being examined.
Water treatment decisions based on incorrect data may be made if sampling is notcorrectly performed. Representative analytical results depend on the water treatmentplant operator ensuring that
• the sample is representative of the water source under consideration• the proper sampling techniques are used• the samples are protected and preserved until they are analyzed• the proper sample containers are used.
Types of SamplesWaterworks operators collect grab samples and composite samples depending on therequirements of the operation or on regulations.
Grab samplesA grab sample is a single water sample collected at any time. Grab samples show the watercharacteristics at the time the sample was taken. A grab sample may be preferred over acomposite sample when
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• the water to be sampled does not flow on a continuous basis• the water’s characteristics are relatively constant• the water is to be analyzed for water quality indicators that may change with time,
such as dissolved gases, coliform bacteria, residual chlorine, disinfection by-products,temperature, volatile organics, certain radiological parameters, and pH.
Figures 2-1 and 2-2 illustrate this point. Figure 2-1 shows the changes in surfacewater dissolved oxygen (DO) over a 24-hour period. A grab sample represents the DOlevel only at the time the sample was taken. DO can change rapidly—for example, becauseof the growth of algae or plants in the water (diurnal effect). On-line process instrumentsare good examples of instruments that perform grab sample analyses; they analyze a con-tinuous string of grab samples and produce a series of individual analyses that, when plot-ted, illustrate trends such as those in the figures.
Figure 2-2 shows that levels of total dissolved solids (TDS) in the same water changevery little. A grab sample can be representative of the water quality in a stable supply suchas a deep well for perhaps a month. Total dissolved solids are a function of the mineralsdissolved from rocks and soil as the water passes over or through them and may changeonly in relation to seasonal runoff patterns. Total dissolved solids in groundwater (e.g.,wells) may also change if certain water-bearing zones in the well become plugged, chang-ing the dilution or zones from which the water is being drawn.
FIGURE 2-1 Example of hourly changes in dissolved oxygen for a surface water source
5
4
3
2
1
012 a.m. 6 a.m. 12 p.m. 6 p.m. 12 a.m.
Dis
solv
ed O
xyge
n, m
g/L
Time of Day
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WATER QUALITY MONITORING 43
Composite samplesIn many processes, water quality changes with time. A continuous sampler–analyzer pro-vides the most accurate results in these cases. Often the operator is the sampler–analyzer,and continuous analysis could prove costly. Except for tests that cannot wait because ofrapid physical, chemical, or biological changes of the sample (such as tests for DO, pH,and temperature), a fair compromise may be reached by taking samples throughout theday at hourly or 2-hour intervals. Each sample should be refrigerated immediately aftercollection. At the end of 24 hours, each sample is vigorously mixed and a portion of eachsample is then withdrawn and mixed with the other samples. The size of the portion is indirect proportion to the flow when the sample was collected (aliquot) and the total size ofsample needed for testing. For example, if hourly samples are collected when the flow is1.2 mgd, use a 12-mL portion of the sample, and when the flow is 1.5 mgd, use a 15-mLportion of the sample. The resulting mixture of portions of samples is a composite sample.In no instance should a composite sample be collected for bacteriological examination.
When the samples are taken, they can either be set aside or combined as they are col-lected. In both cases, they should be stored at a temperature of less than 40°F (4°C) butabove freezing until they are analyzed.
Continuous sampleThis type of sampling is used in on-line or process control sampling devices/instruments.Some of the new regulations call for this type of sampling for the larger systems for chlorine
FIGURE 2-2 Example of monthly changes in total dissolved solids for the surface water source shown in Figure 2-1
500
400
300
200
100
0J F M A M J J A S O N D J
Time, months
Tot
al D
isso
lved
Sol
ids,
mg/
L
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44 WATER QUALITY
residual under the new Ground Water Rule (GWR) and for surface water filtration orgroundwater under the direct influence of surface water (GWUDI) filtration systems. This isalso being used in certain circumstances to monitor distribution systems for chlorine levelsand for other parameters associated with security monitoring. It is also used by larger sys-tems on the incoming surface water for turbidity, pH, and streaming current measurementsfor treatment control. As technology becomes more sophisticated and affordable, this typeof monitoring will become more prevalent in the industry. Some systems use this technologyto monitor levels of nitrate and other specific ions during the treatment process and fluoridelevels of water leaving the treatment facility. Examples of the on-line instruments are shownin Figures 2-3 and 2-4.
Sampling Point SelectionCareful selection of representative sample points is an important step in developing asampling procedure that will accurately reflect water quality. The criteria used to select asample point depend on the type of water sampled and the purpose of the testing. Checkwith primacy regulations as to compliance samples versus process samples. Any sampletaken from a compliance sample tap may have to be reported as a performance sample evenif it is just being collected for process control. Samples are generally collected from threebroad types of areas:
• Raw-water supply• Treatment plant• Distribution system
Raw-water sample pointsThe choice of collection points for raw-water samples depends on the type of system beingsampled. There are at least three general types of systems:
• Raw-water transmission lines• Groundwater (wells)• Rivers, reservoirs, and lakes
Raw-water transmission lines and groundwater sources are sampled directly from thetransmission line or well-discharge pipe. After a sampling point has been selected (prior toany chemical addition or treatment), the pipeline is equipped with a small sample valve ortap, often called a sample cock (Figure 2-5). The valve must be fully opened before sam-pling to flush out any standing water and accumulated sediment. The flow may then beadjusted to achieve the optimal flow for the type of sample being collected. For example, aslow, steady stream to prevent aeration is best for analysis of volatile organics or dissolvedoxygen.
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WATER QUALITY MONITORING 45
Most of the physical factors known to promote mixing in surface waters are absent orare much less effective in groundwater systems. Wells usually draw water from a consider-able thickness of saturated rock and often from several different strata. These water com-ponents are mixed by the turbulent flow of water in the well before they reach the surface
FIGURE 2-3 On-line chlorine residual analyzerCourtesy of HACH Inc.
FIGURE 2-4 On-line particle counter Courtesy of HACH Inc.
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46 WATER QUALITY
and become available for sampling. Most techniques for well sampling and explorationare usable only in unfinished or nonoperating wells. Usually the only means of samplingthe water tapped by a well is to collect a pumped sample. The operator is cautioned toremember that well pumps and casings can contribute to sample contamination. If apump has not run for an extended period of time prior to sampling, the water collectedmay not be representative of the normal water quality. Good records of static and pump-ing levels of the wells should be kept to determine if the well is performing as designed andwhen the sample should be drawn to be representative of the water in the well column.
Rivers. To adequately determine the composition of a flowing stream, each sample (orset of samples taken at the same time) must be representative of the entire flow at the sam-pling point at that instant. The sampling process must be repeated at a frequency suffi-cient to show changes of water quality that may occur over time in the water passing thesampling point.
On small or medium-size streams, it is usually possible to find a sampling point atwhich the composition of the water is presumably uniform at all depths and across thestream. Obtaining representative samples in these streams is relatively simple. For largerstreams, more than one sample may be required. A portable conductivity meter is veryuseful in selecting good sample sites.
Reservoirs and lakes. Water stored in reservoirs and lakes is usually poorly mixed.Thermal stratification and associated depth changes in water composition (such as DO)are among the most frequently observed effects. Single samples can therefore be assumedto represent only the spot of water from which the sample came. Therefore, several sam-ples must be collected at different depths and from different areas of the impoundment toaccurately sample reservoirs and lakes. See Figures 2-6 and 2-7.
FIGURE 2-5 Sample cock attached to pipeline for sampling
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Treatment plant sample pointsTreatment plants are sampled to evaluate the treatment efficiency of unit processes or toevaluate operational changes. Selection of in-plant sample points is an important step indeveloping an overall process control program for a water treatment plant. Samples fromthe points selected can be tested to determine the efficiency of the various treatmentprocesses. The test results will also help to indicate operational changes that will improvecontaminant removal efficiencies or reduce operating costs.
Collection of representative samples in the water treatment plant is similar to sample col-lection in a stream or river. The operator must ensure that the water sampled is representativeof the water passing that sample point. In many water plants, money has been spent topurchase sample pumps and piping only to find that the sample from that point is not rep-resentative of the passing water. A sample tap in a stagnant area of a reservoir or on the
FIGURE 2-6 Routine and transect sample points in a natural lakeSource: Mackenthun and Ingram (1967).
FIGURE 2-7 Routine and transect sample points in a reservoirSource: Mackenthun and Ingram (1967)
Routine Sampling SitesTransect Sampling Sites — Periodic or Seasonal Collections
Dam
MultilevelWater SupplyIntake
Routine Sampling SitesTransect Sampling Sites — Periodic or Seasonal Collections
Roadway
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48 WATER QUALITY
floor of a process basin serves little purpose in helping the plant operator with control ofwater quality. The operator is urged to ensure that each and every sample point is locatedto provide useful and representative data. If the sampling point is improperly located, theoperator should make arrangements to move the piping to a better location. Multiplesample locations for the same analysis point may be needed if changes in plant conditions,such as flow, affect the quality of the sample. (Example: If using a streaming current detectoror other instruments such as an Oxidation-Reduction meter flow can change mixing timesand affect the validity of the value read on the instrument.)
Treatment plants vary widely in the kinds of treatment processes used and the configu-rations of the processes. In general, in-plant sample points are established at every placewhere, because of a treatment method or group of methods, a measurable change is expectedin the treated-water quality. Simply put, if you are adding something to the process, eitherchemically or mechanically, you should have some way of determining the effect. Other in-plant sampling sites may have to be selected and installed for changes in testing needed bychanges in governmental laws and regulations. Figure 2-8 identifies 10 suggested locationswhere process control samples are routinely collected in a plant employing several differenttreatment processes. These locations are described in the following list.
• Between sample points 1 and 2, test results should show a reduction in algae and theassociated tastes and odors (the result of chemical pretreatment), a reduction in sedi-ment load (the result of presedimentation), and a reduction in debris (the result ofscreening).
• Between points 2 and 3, aeration should cause oxidation of iron and manganese and asignificant reduction in undesirable dissolved gases while increasing the oxygen content.
• Between points 3 and 4, the combined effects of coagulation, flocculation, and sedi-mentation should cause a reduction in turbidity and color.
• Water quality changes between sample points 4 and 5 will allow the operator to mon-itor the effectiveness of the softening process.
• Sample points 5 and 6 allow monitoring of the efficiency of filtration in removingturbidity and previously oxidized iron and manganese as well as the reduction in patho-genic organisms.
• Sampling at points 6 and 7 will indicate the efficiency of the adsorption process inremoving organic chemicals.
• Point 8 is used for the measurement of fluoride concentration to ensure that waterentering the distribution system contains the proper level.
• Sampling at point 9 will provide a final check on pH and alkalinity for corrosioncontrol.
• Point 10 is used for monitoring chlorine residual, turbidity, and the presence of coli-form bacteria in the finished water.
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WATER QUALITY MONITORING 49
In the selection of in-plant sample collection points, certain precautions should bekept in mind. Points immediately downstream from chemical additions should be avoidedbecause proper mixing and reaction may not have had time to take place. Always takesamples from the main stream of flow, avoiding areas of standing water, algae mats, andfloating or settled debris.
Finished-water sample points are normally established downstream of the final treat-ment process at or just before the point where the water enters the distribution system,such as the point of discharge from the clearwell. For example, turbidity samples requiredby the National Primary Drinking Water Regulations (NPDWRs) must be collectedbefore the water enters the distribution system while avoiding an area where added chemi-cals (e.g., lime or corrosion inhibitors) may affect the results.
Distribution system sample pointsRepresentative sampling in the distribution system is an indication of system water quality.Results of sampling should show if there are quality changes in the entire system or parts ofit, and they may point to the source of a problem (such as tastes and/or odors). Samplingpoints should be selected, in part, to trace the course from finished-water source (at the wellor plant) through the transmission mains, and then through the major and minor piping ofthe system. A sampling point on a major transmission main, or on an active main directlyconnected to it, would be representative of the plant effluent water quality.
FIGURE 2-8 Suggested in-plant sample points (indicated by numbered circles)
8
RawWater
1 2 3
ChemicalPretreatment
Screening
Presedimentation
Microstraining
AerationChemical Addition
Fluoridation
Flocculation
Coagulation
Adsorption Filtration
Softening
56
7
4
109
Sedimentation
Clearwell
Stabilization Disinfection
To theCommunity
PreliminaryTreatment
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50 WATER QUALITY
Sample points in the distribution system are used to determine the quality of waterdelivered to consumers. In some cases, the distribution system samples may be of signifi-cantly different quality than samples of finished water at the point of entry to the distribu-tion system. For example, corrosion in distribution system pipelines can cause increases inwater color, turbidity, taste and odor, and physical constituents such as lead and copper.Microbiological growth may also be taking place in the water mains, which degradeswater quality. In addition, a cross-connection between the distribution system and asource of contamination can result in chemical or microbiological contamination of thewater in the system.
Most of the samples collected from the distribution system will be used to test forcoliform bacteria and chlorine residual. Others may be used to determine water qualitychanges. Still others will be used to test for maximum contaminant levels (MCLs) of inor-ganic and organic contaminants and for compliance with the Lead and Copper Rule, asrequired by the applicable drinking water standards. Distribution system sampling shouldalways be performed at locations representative of conditions within the system. Radio-logical samples must be from the source water supply under current regulation.
The two major considerations in determining the number and location of samplingpoints, other than those required by regulation, are that they should be
• representative of each different source of water entering the system• representative of conditions within the system, such as dead ends, loops, storage facil-
ities, and pressure zones.
The precise location of sampling points depends on the configuration of the distribu-tion system. The following examples provide some general guidance for sample pointselection.
Example 1. Figure 2-9 provides an example of how sample points may be selected for asmall surface water distribution system serving a population of 4,000. This is a typicalsmall branch system having one main water line and several branch or dead-end waterlines. For this system, a single point, A, is sufficient for turbidity monitoring. This point isrepresentative of all treated water entering the distribution system.
For a community of 4,000, the NPDWRs require a minimum of four bacteriologicalsamples per month to be taken at four different points in the system. Point B representswater in the main line, and point C represents water quality in the main-line dead end.Points D and E were selected to produce samples representative of a branch line and abranch-line dead end, respectively.
Consideration of how often and at what times these points are sampled is also neces-sary to ensure that the samples accurately represent conditions in the distribution system.Although the minimum requirement of four samples per month could be met by collectingsamples from all points on one day, this sampling frequency would not produce samplesthat represented bacteriological conditions within the system throughout the month. A
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WATER QUALITY MONITORING 51
better program would be to sample points B and E at the beginning of the month andpoints C and D at mid-month. Sampling should be representative both in location and intime.
Although this type of program is adequate to meet the minimum monitoring require-ments of the NPDWRs, good operating practices would include periodic sampling at eachdead end and several additional sampling points within the distribution system, with sam-ples taken each week. The exact number and location of these operational sampling pointsdepend on the characteristics of the specific system and on state requirements.
Chlorine residual samples should be taken from each sample point when bacteriolog-ical samples are collected and should be analyzed within 15 minutes of sampling, prefera-bly at the sample location. Sampling for routine water chemistry, along with the requiredsampling for inorganic and organic chemicals, also can be conducted at one of the coli-form sampling points.
Sampling for a similar system using a groundwater source would be the same, exceptthat turbidity sampling generally is not required and samples for organic chemical analy-sis must be collected at each well.
Example 2. Figure 2-10 illustrates a typical small-loop distribution system having onemain loop and several branch loops, serving a population of 4,000. One turbidity samplepoint, A, is sufficient because that point is representative of all treated water entering thedistribution system.
For bacteriological sampling, two sampling points, B and C, are adequate. Point B isrepresentative of water in the main-line loop, and point C is representative of water in oneof the branch-line loops. To produce the required minimum of four samples per month,points B and C can be sampled on alternate weeks, or additional similar sampling pointscan be selected. However, good operating practice would include two to three times thisnumber of samples, depending on the characteristics of the particular system. As with the
FIGURE 2-9 Sampling points (indicated by x) in a typical small-branch distribution system
Main Water LineCreek
B
D
AE
C
Branch Water Lines Population Served = 4,000
Treatment Plant
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52 WATER QUALITY
system in the previous example, chlorine residual samples should be taken whenever bac-teriological sampling is performed.
Example 3. Figure 2-11 illustrates a system serving a population of 17,440 that obtainswater from both a creek and a well. The distribution system has the features of both thebranch and the loop systems shown in Figures 2-9 and 2-10.
To determine sample-point locations, the following four questions should be considered:
1. What tests must be run?2. From what locations will the samples be collected?3. How often must the samples be taken?4. How many sampling points will be needed?
The answers to the first and third questions—what tests must be run and how often—mayvary from state to state, and they are also likely to change periodically in response tochanges in federal requirements.
Additional samples may also be required for the system’s own quality control (QC)program. Examples include taste and odor, color, pH, TDS, iron, manganese, and het-erotrophic plate count.
Once the tests and test frequencies have been determined, the number and specificlocations of sampling points must be selected. The NPDWRs require a turbidity sampleto be taken at each point representative of the filtered surface water that enters the distri-bution system. Because waters from parallel treatment plants enter two separate clearwellsin Figure 2-11, two turbidity sampling points are required (points 11 and 12). The well willnot have to be sampled for turbidity, but periodic sampling directly from the well forchemical quality analysis will be required as directed by the state.
In the selection of sample points that will be representative for coliform analysis, avariety of factors must be considered:
FIGURE 2-10 Sampling points (indicated by x) in a typical small-loop distribution system
B
A
C
Treatment Plant
Branch Loop Main Loop
Population Served = 4,000
Creek
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WATER QUALITY MONITORING 53
• Uniform distribution of the sample points throughout the system;• Location of sample points in both loops and branches;• Adequate representation of sample points within each pressure zone;• Location of points so that water coming from storage tanks can be sampled;• For systems with more than one water source, location of sample points in relative
proportion to the number of people served by each source.
On the basis of these fundamental considerations, bacteriological sample points canbe selected. A treatment plant serving a community with a population of 17,440 must test20 coliform bacteria samples per month, according to the NPDWRs. After a carefulreview of the configuration of the distribution system layout, 10 coliform bacteria samplesites were selected. The reasons for the selection of each point shown in Figure 2-11 are asfollows for bacteriological purposes only:
• Point 1 is on the main loop in the high-pressure zone; it should produce representativesamples for that part of the system.
• Point 2 is on the branch loop in the high-pressure zone, representative of storage flowto the system.
FIGURE 2-11 Sampling points (indicated by solid dots) in a medium-size system with surface and groundwater sources
Cre
ek
2
38
1 10 Storage
Storage Storage4
513
Clearwell 1
Clearwell 2
12
11
TreatmentPlant 2
TreatmentPlant 1
BoosterPump
CheckValves
Population Served = 17,440
High-Pressure Zone
Low-Pressure Zone9
WellWaterSource
6
7
z z
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54 WATER QUALITY
• Point 3 is on a dead end. Some authorities advise against dead-end sampling pointsbecause they do not produce representative samples. However, consumers do takewater from branch-line dead ends. In the example, there are seven branch-line deadends that no doubt serve significant numbers of consumers. It is representative to haveone or two sample points on these branch lines at or near the end. If there are indica-tions of chlorine residual decline or bacteriological problems in water sampled atbranch-line dead ends, hydrants and blowoff valves should be flushed and branchlines resampled immediately to determine if the problem has been corrected. If theproblem persists, additional investigation is needed to locate the condition contribut-ing to the problem.
• Point 4 is located on the main loop of the low-pressure zone and represents waterfrom treatment plant 2, the well water source, the storage tanks, or any combinationof these (depending on system demand at sampling time).
• Point 5 allows for sampling of water flowing into the system from storage.• Points 6 through 9 were selected by uniformly distributing points in the low-pressure
zone, the zone that serves the major part of the community.• Point 10 was selected as representative of a branch-line dead end in the high-pressure
zone, just as point 3 was selected in the low-pressure zone.• Points 11 and 12, as stated previously, are used as turbidity monitoring points.• Point 13 was added to monitor a dead-end branch that is fairly isolated from other
sampling points yet serves a large population.
Sample faucetsOnce representative sample points have been located on the distribution system map, spe-cific sample faucets must be selected. In many cases, suitable faucets can be found insidepublic buildings such as fire stations or school buildings, inside the homes of water systemor municipal employees, or inside the homes of other consumers. The sites selected shouldhave a service line of reasonable size and a good record of water usage. (For example, insome instances in public buildings such as firehouses or schools, a small-diameter serviceline off a large-diameter fire service line does not provide a representative sample. Becausethe fire line may never be used, or may only be tested on a scheduled program, water in theline could become stale, that is, lose its chlorine residual, become oxygen depleted, dis-solve some of the main or sediment in the stagnant pipe.)
In smaller water systems, special sample taps are not available. Therefore, customers’faucets must be used to collect samples. Indoor taps are best, if available. Front-yard out-side faucets on homes supplied by short service lines (i.e., homes on the same side of thestreet as the water main) will suffice if there are no other options. Submerging the ends ofthese faucets in bleach or swabbing the tap with bleach or hydrogen peroxide (again, checkwith your drinking water primacy agency for acceptable method) first is one way to ensure
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that the tap will not taint the sample. However, the disinfectant must be flushed from thetap so it does not enter the sample and produce possible false negative results.
Contact the person in the home and obtain permission to collect the sample. If no oneis to be home, disconnect the hose from the faucet if one is attached, and do not forget toreconnect the hose after you have collected the sample. Open the faucet to a convenientflow for sampling (usually about half a gallon per minute). Allow the water to flow untilthe water in the service line has been replaced twice. Because 50 ft (15 m) of 0.75-in. (18-mm) pipe contains more than 1 gal (3.8 L), 4 or 5 minutes will be required to replace thewater in the line twice. You can check the water temperature and/or chlorine residual todetermine if water coming from the tap matches the quality of the water in the area. Col-lect the sample, being sure the sample container does not touch the faucet.
Do not try to save time by turning the faucet handle to wide open to flush the serviceline. This will disturb sediment and incrustations in the line that must be flushed outbefore the sample can be collected.
For sampling, it is also best to try to find a faucet that does not have an aerator. If afaucet with an aerator must be used, follow the state primacy agency’s recommendationon whether the aerator should be removed for sample collection.
Once a representative sample point has been selected, it should be described on thesample record form and placed in the appropriate sample plan such as the one requiredfor the Total Coliform Rule or Lead and Copper Rule so it can be easily located for futuresample collection.
Collection of SamplesThe steps described in the following sections are general sample collection procedures thatshould be followed regardless of the constituent tested. Special collection proceduresrequired for certain tests are described in succeeding chapters.
Only containers designed for water sampling and provided by the laboratory should beused. Mason jars and other recycled containers cannot be trusted to function properly nomatter how well they are cleaned, and they are generally not accepted by a laboratory forwater analysis. Some laboratories reuse sample containers by washing them under carefullycontrolled conditions and sterilizing them prior to reuse. In other cases, it has been foundmore economical to dispose of used bottles and provide only new ones for collection.
When a container with a screw-on lid is used, the lid should be removed and heldthreads down while the sample is collected in the container. The lid can easily be contami-nated if the inside is touched or if it is set face down or placed in a pocket. A contaminatedlid can contaminate the sample, which will necessitate resampling, causing a great deal ofunnecessary time and expense.
Raw-water sample collectionIf no raw-water sample tap is available and the sample must be taken from an open bodyof water, the following procedures should be used.
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On a well supply, if no raw-water sample tap is available, the well should be put towaste with any treatment shut off, the samples collected, the treatment restarted, and thewell placed back in service. A clean, wide-mouth sampling bottle should be used for raw-water sampling. The bottle should not be rinsed; this is especially important if the bottlehas been pretreated or contains a preservative. The open bottle should be held near itsbase and plunged neck downward below the surface of the water. The bottle should thenbe turned until the neck points slightly upward for sampling, with the mouth directedtoward any current present. Care must be taken to avoid floating debris and sediment. In awater body with no current, the bottle can be scooped forward to fill the bottle. Once thebottle has been filled, it is retrieved, capped, and labeled.
If the sampler is wading, the sample bottle should be submerged upstream from thatperson. If a boat is being used for stream sampling, the sample should be taken on theupstream side.
When samples are being taken from a large boat or a bridge, the sample bottle shouldbe placed in a weighted frame that holds the container securely. The opened bottle andholder are then slowly lowered toward the water with a rope or with the handle that comeswith certain devices available through water supply equipment catalogs, dissolved oxygensampling cans, “swing samplers” on poles, long handled dippers, weighted bailers. Whenthe bottle or sample device approaches the surface, the unit is dropped quickly into thewater. Slack should not be allowed in the rope because the bottle could hit bottom andbreak, or it could pick up mud and silt. After the bottle is filled, it is pulled in, capped, andlabeled. There are also specialized sampling devices to be used as required for specificsamples. For example, for DO, the device with the sample bottles is lowered into the waterand then the stopper is remotely removed, the sample container is filled, and the stopper isreplaced before the unit is removed from the water. This type of device can also be usedwhen sampling at a certain depth to ensure the water is from the zone desired.
Treatment plant sample collectionThe procedure used to collect samples from an open tank or basin or in an open channel ofmoving water is essentially the same as for raw-water sampling. Treatment plants should beequipped with sample taps. These faucets provide a continuous flow of water from variouslocations in the treatment plant, including raw-water sources. In some plants these taps donot run continuously because of operational constraints, so the operator may have to turnthe taps on and run the water for a specific period of time to obtain a representative sample.To collect a sample, the operator or laboratory technician draws the required volume fromthe sample tap. Figure 2-12 shows a typical bank of sample faucets in a laboratory.
Distribution system sample collectionOnce the distribution system sample locations have been selected, sample collection con-sists of a few simple, carefully performed steps. First, the faucet is turned on and set toproduce a steady, moderate flow of water (Figure 2-13). If a steady flow cannot be
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obtained, the tap should not be used. The water is allowed to run long enough to flush anystagnant water from the service line. (The important exception to this procedure is withsamples collected for lead and copper analyses; these must be first-draw samples collectedimmediately after the faucet has been opened.) Depending on the length of the serviceline, as mentioned before, this process can take from 2 to 5 minutes or longer. The line isusually flushed when the water temperature changes (depending on climate and source,the temperature may increase or decrease) and stabilizes. The sample is then collectedwithout the flow changing. The sample bottle lid should be held threads down duringsample collection and replaced on the bottle immediately. If the lid must be set down dur-ing the sampling process, it should be placed threads up and protected from splatter orfalling matter (rain, for example) that could contaminate the sample. The final step aftersampling is to label the bottle.
FIGURE 2-12 Sample faucets in a laboratory
FIGURE 2-13 Sample faucet should be set to produce a steady, moderate flow
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58 WATER QUALITY
A once common practice was to flame the outside of a faucet. This procedure is nolonger recommended. Experience showed that the flame could not be held on the faucetlong enough to kill all the bacteria on the outside of the faucet without potential damageto the faucet. Many faucets are now made partly or entirely of plastic, which will quicklymelt if high heat is applied. The current common practice is to dip the faucet into a smallcontainer of bleach or swab it with bleach or other approved disinfectant.
Samples should not be collected from sill cocks or other faucets with hose threadsunless local regulations require it and the threads can be thoroughly cleaned. Because ofthe way they are constructed, these faucets do not usually throttle to a smooth flow. Also,if any water splashes up onto the threads and then drains into the sample bottle, it willbring with it contaminants from the outside of the faucet.
Special-purpose samplesOccasionally a water utility may need to collect samples for special testing purposes. Pro-cedures in such cases depend on the reason for the sampling.
For example, a consumer may have complained about taste, odor, or color in thewater. In such a case, samples are collected from the consumer’s faucet to determine thesource of the problem. The faucet is opened and a sample taken immediately. This samplerepresents the quality of water standing in the service line. The water is then allowed torun for 2 to 5 minutes or until the water temperature changes, so that the standing water inthe service line is completely flushed out; then a second sample is taken. The second sam-ple is fresh from the distribution system. Comparing test results from the two samplesoften helps to identify the origin of the problem causing the consumer complaint.
Customer complaints of taste, odor, or color are often caused because the consumer’swater heater, water softener, or home water-treatment device is not maintained or operatingproperly. If the hot-water supply is suspected, the first sample should be collected from thehot-water tap. The tap is turned on and allowed to run until the water is hot before the sampleis collected. A second sample representing the water in the service line should be taken fromthe cold-water tap as previously described. Comparing the test results from the two sampleswill help identify the origin of the problem unless a whole-house filter or treatment device is inuse. In that case, it may be necessary to collect a sample from an outside untreated faucet, themeter connection, or a neighbor’s faucet for comparison with an untreated sample.
There are many other reasons for taking special-purpose samples. The previous exam-ple emphasizes the importance of knowing what the sample test results will be used for sothat the sample collected will be representative of the conditions tested.
MONITORING FOR CHEMICAL CONTAMINANTSDrinking water may contain contaminants considered a threat to the public. The contami-nants of concern may occur naturally in the water, be human-made, or be formed during thewater treatment process. The chemicals are broken into four general classes for regulation:
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WATER QUALITY MONITORING 59
1. Inorganic chemicals (IOCs)2. Synthetic organic chemicals (SOCs)3. Volatile organic chemicals (VOCs)4. Radionuclides (covered in Chapter 8)
Monitoring RequirementsThe need to establish regulations for new chemical contaminants has presented USEPAwith the problem of creating, adapting, proving and promulgating analytical techniques.The method must be for a specific chemical and not for a “contaminant” defined by aphysical description such as a boiling fraction; i.e. an example of this is kerosene which ispetroleum distillates which boil between 150°C and 275°C which results in a mixtureorganic chains of 6 to 16 carbon atoms in each compound. Before a requirement to moni-tor for a contaminant can be imposed, the testing methods must be developed to ensurethat an adequate number of laboratories will be available to perform the tests and thatthey will get consistent, reliable results. Many of the chemicals now being added to the listof regulated contaminants must be analyzed at the parts-per-billion level or in evensmaller concentrations.
Faucets selected should be on the lines connected directly to the main. Only cold-water faucets should be used for sample collection. A sampling faucet must not be locatedtoo close to a sink bottom. Contaminated water or soil may be present on the exteriors ofsuch faucets, and it is difficult to place a collection bottle beneath them without touchingthe neck interior against the faucet’s outside surface. In most instances samples should notbe taken from the following types of faucets (Figure 2-14):
• Leaking faucets, which allow water to flow out around the stem of the valve anddown the outside of the faucet.
• Faucets with threads.• Faucets connected to home water-treatment units, including water softeners and hot-
water tanks.• Faucets that swivel, since the swivel joint may act as a siphon and bring in contamination • Faucets with single-lever handles that do not guarantee only the cold-water sample is
being selected.
LABORATORY CERTIFICATIONEach of the approximately 155,000 public water systems affected by the Safe DrinkingWater Act (SDWA) must routinely monitor water quality to determine if the water is ade-quately protected from regulated microbiological, chemical, and radiological contaminants.It is imperative that the analyses for all of this monitoring be performed by standard meth-ods approved for compliance testing so that the results are comparable for all systems. Con-sequently, states are required by federal regulations to consider analytical results from water
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systems only if samples have been analyzed by a certified laboratory. Some exceptions aremeasurements for turbidity, chlorine residual, temperature, and pH, which may be per-formed by a person acceptable to the state using approved equipment and methods.
Federal regulations require each state with primary enforcement responsibility to haveavailable laboratory facilities that have been certified by USEPA, with capacities sufficientto process samples for water systems throughout the state. Certified laboratories fall intothe following general classes:
• State-operated laboratories• Water-system laboratories• Commercial laboratories
In most states, the necessary capacity is provided by a combination of all three types oflaboratories. Some laboratories may be certified to perform only one type of analysis; forinstance, some laboratories are set up to handle only microbiological analyses. Analysesrequiring expensive equipment and highly trained technicians, such as for organic chemicaland radiological monitoring, are also generally handled by specialized laboratories.
FIGURE 2-14 Types of faucets that should not be used for sampling
TreatmentUnit
Leaking FaucetsFaucets With Threads
Drinking FountainsFaucets Connected toHome Treatment Units
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WATER QUALITY MONITORING 61
Consistency among laboratories in analytical results is overseen by the USEPA andby state primacy programs for each of the types of analyses for which the laboratories arecertified. Periodically, an independent vendor contracted by USEPA provides to each lab-oratory carefully prepared proficiency testing samples containing a known concentrationof a contaminant. The values of the samples are unknown to the laboratory, and its staffmust be able to determine the contaminant concentration within an appropriate toleranceto maintain the laboratory’s certification. The results determined by the laboratory aresubmitted to the agency having primacy for laboratory certification for the particularstate.
Historically, most states have operated their own laboratories to process water sys-tem samples. But the number of samples has increased severalfold in recent years, so it isdifficult for the states to continue providing laboratory service with state funding only.Some states have instituted charges to water systems to help fund the laboratory services.Other states only process a certain number of samples from any one water system, and ifmore are required, commercial laboratories must be used.
RECORD KEEPING AND SAMPLE LABELINGRecords should be kept for every sample that is collected. A sample identification label ortag should be filled out at the time of collection. Each label or tag should include at leastthe following information:
• Water utility name• Water system’s public water system identification number• Date sample was collected• Time sample was collected• Location where sample was collected• Type of sample—grab or composite• Tests to be run• Name of person sampling• Preservatives used• Bottle number
The samples provided to laboratories should always be clearly labeled. The informa-tion on the label should also be entered on a record-keeping form that is maintained as apermanent part of the water system’s records and placed on the chain-of-custody formssubmitted to the laboratory. Each laboratory may have its own forms that request therequired information for compliance with regulations.
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SAMPLE PRESERVATION, STORAGE, AND TRANSPORTATIONSamples cannot always be tested immediately after they are taken. Ensuring that the level ofthe constituent remains unchanged until testing is performed requires careful attention totechniques of sample preservation, storage, and transportation. It is also extremely impor-tant that records be kept of the chain of custody of samples collected for SDWA compliance.
Preservation and StorageAfter a sample has been collected, its quality may change because of chemical and/or bio-logical activity in the water. Some characteristics (alkalinity, pH, dissolved gases, disinfec-tant residuals, temperature, and odor) can change quickly and quite significantly, and sosamples to be analyzed for these parameters should not be stored under any conditions.The tests for disinfectant residuals, pH and temperature must be completed in the field attime of collection. Other parameters, such as pesticides and radium, change more slowlyand much less noticeably, and these samples can usually be stored for considerable lengthsof time if necessary.
To extend the storage time of samples requiring chemical analysis, sample-preservationtechniques have been developed that slow the chemical or biological activity in the sample.This allows it to be transported to the laboratory and tested before significant changesoccur.
Sample preservation usually involves the following steps:
• Refrigeration and/or• Chemical preservatives
For some samples storage time can be prolonged by keeping samples refrigerateduntil the analysis is performed. In some cases, it is recommended that samples be trans-ported or shipped to the laboratory in a portable cooler containing an ice pack.
Often the laboratory provides bottles for specific analyses with the preservative alreadyadded. It is particularly important not to allow these containers to overflow as they arefilled, or some of the preservative will be lost. These containers must also be kept out of thereach of children, because the preservative material could be harmful to a child who opensa container. If preservatives are to be added by the sampler, specific instructions on the pro-cedures should be obtained from the laboratory that will perform the analyses.
Time of samplingMost laboratories do not maintain a full staff on weekends, so they generally request thatsamples with short holding times, such as bacteriological samples, be collected andshipped early in the week. If a sample arrives on a weekend and cannot be processed, thedelay will probably exceed the required holding time and the sample will be rejected. How-ever, most laboratories accept emergency samples on weekends.
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Samples that must be submitted within a specified compliance period should gener-ally be collected and sent to the laboratory early in the compliance period. Some of theproblems that can require resampling are described in the following list:
• The sample is frozen or broken during shipment.• The sample is lost or delayed in shipment and arrives at the laboratory after the spec-
ified holding time has elapsed.• The laboratory makes an error in processing the sample.• The laboratory analysis is inconsistent or shows an increase in the MCL, and another
sample to confirm the results is required.• The sample was not properly preserved or was too warm, or no preservative was present.• The sample container was not the proper container for the required sample, size, vol-
ume, or material.
Sampling early in the compliance period ensures that time is available for one or moreresamplings, if necessary, before the end of the period. If resampling has not been com-pleted before the end of a compliance period, a water system is usually deemed out ofcompliance and will be instructed by the state to provide public notification.
TransportationIf samples arrive at a laboratory past the specified holding time following collection, thelaboratory must reject the samples. New sample bottles must then be shipped to the watersystem and another set of samples will have to be collected and shipped back.
The mail is usually the best and easiest method of shipment, except for microbiologicalor certain radiological samples that require delivery within about a 24-hour period. If regu-lar mail service fails to deliver samples reliably within the required time period, overnightshipping services or package delivery services may be tried. In some cases, changing to alaboratory at a different location may improve delivery time. Some water system operatorswho are located near a laboratory have found it best just to drive the samples directly to thelaboratory or arrange with the laboratory for pickup of the samples as part of the analysisprice. Depending on distance and availability of personnel, a bonded courier service may beused.
If samples are shipped, it is important to make sure the bottle caps are tight to pre-vent leakage. Systems that have had bottle caps loosen during shipment have found thatwrapping the lids with electrical or packing tape is an easy method of further securingthem. Samples must be packed in a sturdy container with enough cushioning material toprevent breakage. The box should be marked to indicate which end is up, that the contentsare fragile, that they must not be allowed to freeze, and that priority should be given to theshipment.
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Chain of CustodyAs more and more parameters are added to the list of regulated and unregulated contami-nants, and with the MCLs and MCLGs in the micrograms per liter range, the practice ofgood quality assurance and quality control (QA/QC) procedures becomes very important.One essential part of QA/QC is maintaining a written record of the history of SDWA com-pliance samples from the time of collection to the time of analysis and subsequent disposal.This record, called the chain of custody, is important if the analyses are ever challenged andneed to be defended. Chain-of-custody requirements vary by state, so water system opera-tors should be sure that the requirements for their state are being met.
Field log sheetOne method of establishing the chain-of-custody record is to use a daily field log sheet,which should contain the following information:
• Date the samples were collected• Name of the sampler• List of all the samples collected by the sampler on this date• List of all the sample locations for this date• Time of day each sample was collected• Comments concerning any unusual situations• Signature of the individual receiving the samples from the sampler• Date and time the samples were received by the laboratory• Location or identification of the laboratory
This log sheet states that the samples were in the custody of the sampler until theywere turned over to the shipper. The laboratory record then follows the history of the sam-ple to disposal.
Sampler’s liabilityIf the results of an analysis of a specific sample are ever questioned, the sampler will beasked to verify that the sample was in his or her custody until it was turned over or sent tothe laboratory. The sampler will be asked to verify that the sample was collected, stored,and transported using proper procedures and that no other person could have in any wayaltered the concentrations of any contaminant(s) present.
Sampler’s responsibilityThe sampler has the basic responsibility to ensure that the sample is properly collected,labeled, stored, and transported to the laboratory. The sample collector must be able totestify that the sample was under his or her custody at all times. The sample collector is
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also responsible for knowing and performing the proper sampling routine for each type ofanalysis required, including preservation.
SELECTED SUPPLEMENTARY READINGSAkers, R. 2009. Current Issues — Ensuring Freshwater Resources for Southwest Florida.
Journ. AWWA, 101(5):24–28.
Carey, E. 1992. Responsible Sampler, Lab’s Best Asset. Opflow, 18(8):5.
———. 1992. Water Quality Only as Good as the Sample. Opflow, 18(8):5.
Eaton, A., G. Lynch, and K. Thompson. 1993. Getting the Most From a ContractLaboratory. Jour. AWWA, 85(9):44.
Feige, M.A., C. Madding, and E.M. Glick. 1993. USEPA’s Drinking Water LaboratoryCertification Program. Jour. AWWA, 85(9):63.
Lay, T. 1989. Proper Sampling Helps Systems Comply With SDWA. Opflow, 15(1):3.
Lee, B.H., R.A. Deininger, and R.M. Clark. 1991. Locating Monitoring Stations inWater Distribution Systems. Jour. AWWA, 83(7):60.
Mackenthun, K.M., and W.M. Ingram. 1967. Biological Associated Problems inFreshwater Environments. Cincinnati, Ohio: US Department of the Interior, FederalWater Pollution Control Administration.
Pesacreta, G. 2009. Early Warning System Minimizes Water Quality Problems. Opflow,35(1): 24–26.
Rosen, J.S., Jose A.H. Sobrinho, and M. LeChevallier, 2009. Statistical Limitations in theUsefulness of Total Coliform Data. Journ. AWWA, 101(3):68-81.
Sekhar, M. and A. Dugan. 2009. Collect Representative Distribution System Samples.Opflow, 35(1): 20–23.
Stubbart, J.M., W.C. Lauer, and T.J. McCandless. 2004. AWWA Water Operator FieldGuide. Denver, CO: American Water Works Association.
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67
C H A P T E R 3
Water Laboratory Equipment and Instruments
Water treatment processes cannot be controlled effectively unless the operator has someway to check and evaluate the quality of water being treated and produced. Laboratoryquality control tests provide the necessary information to monitor the treatment processesand ensure a safe and good-tasting drinking water for all who use it. By relating labora-tory results to treatment operations, the water treatment or supply system operator canselect the most effective operational procedures, determine the efficiency of the treatmentprocesses, and identify potential problems before they affect finished water quality. Forthese reasons, a clear understanding of laboratory procedures is a must for every water-works operator.
LABWAREThe type of glass most often used in the majority of laboratory bottles, beakers, and othercontainers is heat-resistant borosilicate glass. It is commonly sold under the trade namesPyrex® or Kimax®. This heat-resistant glass can be sterilized repeatedly at high tempera-ture and pressure; can be heated over open flames without shattering; and can also with-stand heat generated from chemical reactions. However, rapid heating and cooling canweaken even heat-resistant glass, eventually causing it to crack or shatter.
Plastic is the second most common labware material and is suitable for many labora-tory purposes. Some types of plastic are resistant to high temperatures and can be auto-claved. Extensive use of plastic labware is a matter of choice. Its principal advantage isthat it is less subject to breakage. Some types of plastic labware are also disposable, whicheliminates the need for laborious cleaning procedures. However, reusable plastic is harderto clean and cannot be used for all chemical analyses. For example, plastic labware shouldnot be used in preparing samples for organic chemical analysis because the plastic mayabsorb the organic compound, causing erroneous results. In certain other tests, such asextractions using organic solvents, the chemicals used may deteriorate plastic almostimmediately. Additionally, plastic labware is easily scratched and marred and eventuallybecomes cloudy with use.
Another labware material is soft (nonheat-resistant) glass, which can be used to storesome dry chemical reagents, such as salts. This material is not recommended for extensivelaboratory use because it breaks easily and cannot be heated.
Some of the common types of laboratory containers are described in the following sections.For all liquid measurements in calibrated glassware discussed, the reading should be
taken at calibration mark matching the bottom of meniscus of the liquid since liquids tend
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to form a concave (bowl-shaped) meniscus at their surface. This phenomenon does nothold true for mercury, which forms a convex (mound-shaped) meniscus. For mercury, readthe top of the meniscus opposite the calibration mark.
All labware used to store a sample, chemical, or reagent should be properly labeled asto the contents for safety. This is important to prevent lost sample, mixing of incompatiblematerials, or other unwanted reactions or conditions affecting health or safety.
BeakersA beaker is a glass jar with an open top, vertical sidewalls, and a lip that simplifies pouringof liquids (Figure 3-1). Common laboratory beakers range in size from 25 to 4,000 mL.The 250- and 500-mL sizes are the most popular. Beakers are used as mixing vessels formost chemical analyses, and an ample supply of various sizes should always be kept onhand for use in a laboratory.
BurettesA burette is a glass tube that is graduated over part of its length and fitted with a stopcock(Figure 3-2). The most common sizes are 10, 25, and 50 mL. The graduations are nor-mally in tenths of a milliliter. Burettes are designed for measuring and dispensing solu-tions during titration, a procedure commonly used when determining the concentration ofa substance in solution. Both glass and plastic burettes are available. Plastic burettes areespecially useful for field tests. “Bottle-top” burettes (Figure 3-2) are also available; theyhave the advantage of being easy to read and allow more rapid titration. When usingburettes for compliance analytical tests, make sure the labware is marked and certified as“Class A,” since these are mandated in the regulations. For process control work you canuse a lower grade of equipment.
FIGURE 3-1 Beakers
200 mL
150 mL
100 mL
50 mL
250 ml
400 mL
200 mL
150 mL
100 mL
50 mL
AP
PR
OX
VO
LUM
E
md 10000
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WATER LABORATORY EQUIPMENT AND INSTRUMENTS 69
Dilution BottlesDilution bottles are also known as milk dilution bottles or French squares. They are auto-clavable glass or plastic vessels used for diluting bacteriological samples for analysis. Thebottles are square (Figure 3-3), with narrow mouths threaded to receive a screw cap. Allbottles have a 160-mL capacity with a mark at the 99-mL level to facilitate 1- to-100-mLdilutions of a sample.
FlasksThere are many types of flasks, each with its own specific name and use (Figure 3-4).Some names, such as distilling and filtering, identify their use. Other names specify the testthey are used for, such as Kjeldahl. All flasks have narrow necks. Erlenmeyer, biochemicaloxygen demand (BOD), and volumetric flasks are the most common types.
FIGURE 3-2 Manual burette (left) and bottletop burette (right) Courtesy of Brinkmann Instruments, Inc.
0
1
2
3
4
19
20
21
22
23
24
25
1020
o
C
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70 WATER QUALITY
FIGURE 3-3 Dilution bottle
FIGURE 3-4 Flasks
13
13
500 mLTC200 40
mLNo. 5643
200 mL
Distilling Flask Kjeldahl Flask
Volumetric Flask
500
400
300
200
100
250
250 ml 200
150
100
Erlenmeyer Flask Filtering FlaskFlorence Flask
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Erlenmeyer flasksOne of the most frequently used pieces of labware is the Erlenmeyer flask. Ranging in sizefrom 100 to 4,000 mL, these flasks are characterized by their bell shape. They are recom-mended for mixing or heating chemicals because they minimize splashing. They are alsofrequently used for preparing and storing culture media. Some Erlenmeyer flasks havespecially designed ground-glass fitted tops that makes them ideal for taste and odor sam-ples. Other Erlenmeyer flasks have screw caps, which allows them to be sealed for storageof a sample or for specialized testing.
Biochemical Oxygen Demand BottlesBOD flasks are frequently used in the laboratory for dissolved oxygen (DO) testing sincethe dissolved-oxygen probes from many manufacturers are designed to fit in them. Theseflasks hold about 300 mL of liquid. They are short, squat rounded flasks with a narrowmouth fitted with a ground-glass top that has space around the top rim to hold water forsealing the samples. In addition to being used for DO and BOD tests, these flasks areappropriate for various other tests requiring a reaction vessel with a tight seal. But bewarethat most of these flasks are made of soft glass and do not take heat shock well.
Volumetric flasksVolumetric flasks have long, narrow necks. They range in size from 10 to 2,000 mL; anetched ring around the neck indicates the level at which the flask’s capacity is reached.Volumetric flasks are used for preparing and diluting standard solutions. Because theseflasks are designed for measuring, they should not be used for long-term storage of solu-tions. Again, make sure that if the flasks are being used in performance testing—either forthe preparation of standards or in the dilution of samples—they are marked and certifiedas Class A labware.
FunnelsThe funnel is a common piece of laboratory equipment. Four of the most frequently usedtypes are shown in Figure 3-5. The general-purpose funnel is used to transfer liquids intobottles or to hold filter paper during a filtering operation. Funnels are made of heat-resistant glass, soft glass, or plastic. There are also several disposable types.
Graduated CylindersGraduated cylinders are tall, slender, cylindrical containers made of glass or plastic(Figure 3-6). They generally have a pour spout and a hexagonal base. They range in sizefrom 10 to 4,000 mL. Graduations are marked in 0.2-mL intervals on the 10-mL size andin 50-mL intervals on the 4,000-mL size. Graduated cylinders are used for measuringliquids quickly but without great accuracy. Polycarbonate cylinders are good for general
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72 WATER QUALITY
use in the water plants since they are clear like glass and the sides do not wet with the liq-uid; thus the surface of the water in this material is flat and there is no confusion overreading the meniscus.
Petri DishesPetri dishes are shallow dishes with vertical sides and flat bottoms. They usually haveloose-fitting covers (Figure 3-7). They are used as containers for culturing standard plate
FIGURE 3-5 Funnels
FIGURE 3-6 Graduated cylinder
Separatory Funnel
Filter Funnel
Büchner Funnel
General-Purpose Funnel
100
90
80
70
60
50
40
30
20
10
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WATER LABORATORY EQUIPMENT AND INSTRUMENTS 73
counts and membrane filters. They may be glass or plastic and should be completelytransparent for optimum visibility of colonies.
Usually dishes measuring 100 mm × 15 mm are used for heterotrophic plate counts(HPCs). A petri dish measuring 50 mm × 12 mm with a tight bottom lid is used to containand culture 47-mm membrane filters. The tight fit retards evaporation loss from bothbroth and agar media, which helps maintain humidity inside the dish.
PipettesPipettes are used for accurate volume measurements and transfer. Three types of pipettesare commonly used in the laboratory—volumetric pipettes, graduated or Mohr pipettes,and serological pipettes.
Volumetric pipettes are available in sizes, such as 1, 10, 25, 50, and 100 mL. They areused to deliver a single volume. Measuring and serological pipettes, however, will deliverfractions of the total volume indicated on the pipette. Volumetric pipettes used for perfor-mance monitoring should be Class A glassware.
To empty volumetric pipettes, hold them in a vertical position so the outflow is unre-stricted. The tip should be touched to the wet surface of the receiving vessel and kept incontact with it until the emptying is complete. Under no circumstance should the smallamount remaining in the tip be “blown out,” that is using air pressure to clear the tip ofthe pipet.
Measuring and serological pipettes should be held in the vertical position. After out-flow has stopped, the tip should be touched to the wet surface of the receiving vessel.Where the small amount remaining in the tip is to be blown out and added, this will beindicated by a frosted band near the top of the pipette.
Use of a pipette filler or pipette bulb is recommended to draw the sample into apipette. Never pipette chemical reagent solutions or water samples by mouth. Use the fol-lowing techniques for best results:
1. Draw liquid up into the pipette past the calibration mark.2. Quickly remove the bulb and place dry fingertip over the end of the pipette.
FIGURE 3-7 Petri dish
Cover
Bottom
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74 WATER QUALITY
3. Wipe excess liquid from the tip of the pipette using laboratory tissue paper.4. Lift finger and allow desired amount, or all, of liquid to drain.
In many types of pipette bulbs and fillers on the market, the flow of liquid from thepipette can be controlled without removing the pipette from the apparatus.
Two kinds of pipettes are generally used. Those with a graduated stem, called Mohrpipettes, can be used to measure any volume up to the capacity of the pipette. Those with asingle measuring ring near the top are called volumetric or transfer pipettes. Typical Mohrand volumetric pipettes are shown in Figure 3-8.
Pipettes marked with the letters TD are designed “to deliver” the calibrated volume ofthe pipette. They will deliver the specified amount if the following conditions are met:
• The pipette is clean.• The pipette is held in a near-vertical position during delivery.• Contact is made between the tip of the pipette and the receiving vessel at the end of
the transfer.
The small drop of solution that will be left in the pipette is accounted for in thepipette’s calibration. If a pipette has two bands ground into the glass at the top, it has beencalibrated for the last drop in the pipette to be blown out.
Pipettes are constructed with the delivery end tapered and the opposite end fire-polishedso that it can be closed easily with a fingertip. For work requiring great accuracy and specifiedvolumes, samples should be measured with a volumetric pipette. If the sample to be measuredis less than 50 mL, it is good practice to use a pipette rather than a graduated cylinder. In gen-eral, transfer or volumetric pipettes should be used when a great deal of accuracy is required.Measurement, or Mohr, pipettes may be used when less accuracy is required.
To repeat, mouth suction should never be used to pipette solutions. Instead, a pipettebulb or filler should be used.
Graduation marks on pipettes must be legible and permanently bonded to the glass.Pipettes should not be allowed to stand overnight in caustic or detergent solutions becausethey may become cloudy or frosted. If pipettes become badly etched or the tips becomechipped, they should be discarded. Such damage can interfere with accurate measurement.
FIGURE 3-8 Mohr pipette (top) and volumetric pipette (bottom)
0123456789
10
mL
TD 10 mL 20o
C
10IN 1/10
10
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WATER LABORATORY EQUIPMENT AND INSTRUMENTS 75
Porcelain DishesPorcelain labware has long been favored for use with samples that are at elevated tempera-tures. Glazed porcelain is nonporous and highly resistant to heat, sudden changes in tem-perature, and chemical attack. Most evaporating dishes and filtering crucibles (calledGooch crucibles) are made of porcelain. These dishes are used for analysis of total sus-pended solids (TSS) and total dissolved solids (TDS). A porcelain evaporating dish and afiltering crucible are shown in Figure 3-9.
Reagent BottlesReagent bottles (Figure 3-10) are made of borosilicate glass because they must be stableand resistant to heat and mechanical shock. The caps, also made of borosilicate glass, areusually ground-glass stoppers with flat tops, grip tops, or penny-head tops. Tops may alsobe plastic.
Reagent bottles should be used exclusively for storing reagents in the laboratory. Theyshould be clearly labeled with the following information:
• Name of the chemical and chemical formula• Concentration of the chemical
FIGURE 3-9 Evaporating dish (left) and filtering crucible (right)Courtesy of CoorsTek
FIGURE 3-10 Reagent bottle
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• Date the reagent was prepared or received• Initials of the person who prepared or received the reagent• Expiration date of the reagent
Some reagent bottles are supplied with etched or raised-glass letters; others have aspecially ground area for marking. Some reagents, such as those that are fluoride based,should be stored only in plastic reagent bottles.
Sample BottlesWide-mouth sample bottles are used for water sample collection, primarily because it iseasier and quicker to fill them than to fill narrow-mouth bottles. In bacteriological sam-pling, there is less chance of contamination by splashing if wide-mouth bottles are used.Glass sample bottles should be made of borosilicate or corrosion-resistant glass, withmetal or plastic closures equipped with nontoxic leakproof liners (Figure 3-11).
Plastic bottles for bacteriological and chemical samples offer the advantages of beinginexpensive, lightweight, breakage resistant, and, depending on type, disposable. Autocla-vable polypropylene bottles are available for collecting microbiological samples, but theyshould be discarded when they become brittle or discolored.
Bottles used to collect water for organic chemical analysis must be specific for theintended analysis (i.e., volatile organic compounds, synthetic organic compounds). Onlyborosilicate glass, polytetrafluoroethylene (PTFE; the trade name is Teflon™), or stainless-steel labware should be used. Plastic labware made from polyethylene and polypropylene, isnot acceptable for organic chemical analysis. However, plastic caps with PTFE liners maybe used.
Some glassware, often referred to as amber glassware, is tinted a brown or reddishcolor. It retards light entering the sample bottle to reduce the possible deterioration oflight-sensitive chemicals in the sample. Check with the laboratory running the tests tomake sure you are using the proper container.
FIGURE 3-11 Sample bottle
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WATER LABORATORY EQUIPMENT AND INSTRUMENTS 77
Test Tubes and Culture TubesTest tubes are hollow, slender glass tubes with rounded bottoms, open tops, and flared lips(Figure 3-12). Culture tubes are similar but have plain lips (Figure 3-13).
Test tubes and culture tubes can be used for a variety of general laboratory tests. Theymay be made of disposable plastic, disposable glass, heat-resistant glass, or special-purposeglass.
Uses for culture tubes include multiple-tube fermentation tests for bacteria, biochem-ical tests for bacterial identification, and stock culture collections.
Cleaning LabwareIt is important to clean labware as soon as possible after use. This practice will ensure anadequate supply of clean labware and will prevent the formation of stains. Pipettes andburettes, for example, should be rinsed promptly after use. Good labware-cleaning proce-dure involves two washes and two rinses:
• Detergent wash• Acid wash with 10 percent hydrochloric acid• Hot tap-water rinse• Distilled-water rinse
Any good nonphosphate household detergent is adequate for cleaning most labware.Special detergents are also available from laboratory supply outlets. Liquid detergents arepreferable to nonliquid types.
Dissolved matter should not be allowed to dry on labware, because if it is not com-pletely removed, it could contaminate future analyses. If stubborn stains or crusty chemi-cal residues remain after normal cleaning procedures, glassware should first be washedwith a cleaning solution, such as an acid-dichromate type or other form of strong cleaningagent. These solutions are available either ready-made or as concentrates.
Labware used in organic chemical analysis must be cleaned with particular care—even trace amounts of organic contaminants must be removed. Specific dedicated labwareshould be used for organic chemical analysis.
FIGURE 3-12 Test tube
FIGURE 3-13 Culture tube
125 × 15 mm
125 × 15 mm
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MAJOR LABORATORY EQUIPMENTFor a laboratory to operate properly and perform basic analyses, several major pieces ofequipment must be available. These are described in the following sections.
Colony CountersA colony counter (Figure 3-14) is used to count bacterial colonies for the HPC test. Com-mercially manufactured colony counters magnify and backlight petri dishes so that bacterialcolonies grown in the dishes can be counted. Colony counters generally contain a black con-trast background with a ruled counting plate to make counting easier. The viewing area isilluminated from below the culture dish. The viewing field is magnified 1.5 times by a 5-in.(130-mm) magnifying glass.
DesiccatorsA desiccator is a sealable container used to hold items in the absence of moisture beforethey are weighed on an analytical balance. The desiccator serves two important functions:(1) It provides a place where heated items can cool slowly prior to weighing, and (2) it pro-vides a dust- and moisture-free environment so that items being cooled will not gain mois-ture or contaminant weight before they are weighed. A chemical (such as dry calciumsulfate) placed in the bottom of the desiccator removes moisture from the air within theenclosure.
Glass desiccators with tight-fitting glass covers and ground-glass flanged closures(Figure 3-15) were the standard for years. Currently, desiccating cabinets made of fiber-glass or stainless steel and glass with pliable seals are also used. Laboratories use them tostore opened containers of media and maintain the dryness of equipment as required.
The desiccator should be properly maintained and monitored. The seals, whethermade of compressible material or sealing “grease” for ground-glass units, should bechecked to ensure an airtight fit. There should be a drying indicator in the bottom of thedesiccator that should be checked daily to determine if the water-absorbing capacity of thedrying agent is close to being exhausted. Drying agents in which the indicator is manufac-tured into the agent are available to let you know when regeneration is needed. The dryingagent should be regenerated or replaced before its capacity has been reached. Any crackor breach in the desiccator wall or top should be repaired, or if that is not feasible, the unitor part should be replaced.
Fume HoodsA fume hood is a large enclosed cabinet that contains a fan to vent fumes out of the labo-ratory. When used properly, the hood is one of the most important devices for preventinglaboratory accidents. A typical fume hood (Figure 3-16) contains a glass or clear acrylic(trade name Plexiglas™) door that can be closed to isolate the contents under the hood
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FIGURE 3-14 Colony counter Courtesy of Reichert, Inc.
FIGURE 3-15 Glass desiccatorCourtesy of Corning Life Sciences
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from the main laboratory. A convenient fume hood arrangement includes waste drains,electrical outlets, gas taps, and air and vacuum pressure taps, all located within the fumehood cabinet.
All tests that produce unpleasant or harmful smoke, gas, vapors, or fumes should beconducted under a fume hood. Whenever heat is used in a test procedure, the test shouldbe conducted under a fume hood. The hood contains the fumes, and the hood door, ifpartially lowered, can protect the operator's face and upper body from accidental splash-ing while the test is being performed. Containers holding liquids or solids that give offharmful vapors can also be stored in this area until they are used, removed from the labo-ratory, or properly disposed of.
IncubatorsAn incubator is an artificially heated container used in growing bacterial cultures formicrobiological tests. The three most common types of incubators are dry-heat incuba-tors, low-temperature incubators, and water-bath incubators.
FIGURE 3-16 Fume hood Photo reprinted with permission of Labconco Corp.
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Dry-heat incubatorsDry-heat incubators contain a heating element capable of holding temperatures to within±0.5°C of the desired incubation setting. They are useful for total coliform and HPC anal-yses that require a temperature of 35°C ± 0.5°C. These incubators usually have a tempera-ture range of 30°C to 60°C. Because they contain a heating element only, they cannot holdtemperatures below room temperature if there are applications that require this tempera-ture range in an elevated temperature environment.
There are two types of dry-heat incubators: gravity convection and mechanical con-vection. Mechanical-convection incubators (Figure 3-17) have air-circulating fans thathelp keep a constant temperature throughout the interior and therefore are more effectivein maintaining temperature tolerance limits than are gravity-convection incubators.
Low-temperature incubatorsLow-temperature incubators are used for incubation at temperature ranges from –10°C to50°C with ±0.3°C uniformity. These incubators are refrigerators that contain a heatingelement and a thermostat. They are most frequently used for BOD determinations.
Water-bath incubatorsWater-bath incubators are used for maintaining a more constant incubation temperaturethan is possible with dry-heat incubators. They are also used for many common analysesin which reactions must be completed with reagents or mixtures at a specified temperature.
FIGURE 3-17 Mechanical convection Courtesy of Precision/Napco
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Water baths used as incubators for fecal coliform analyses must maintain a constant tem-perature of 44.5°C ± 0.2°C. Water baths are capable of limiting variation from the desiredsetting to ±0.2°C if the bath is covered and the water is circulated or gently agitated.
Most standard water baths are equipped only with heating elements to control tem-perature. These units operate in a range from room temperature to 100°C. Water bathsthat have both refrigeration and heating elements and an operating range of 0°C–100°Care also available.
Jar Test ApparatusA jar test apparatus is an automatic stirring machine equipped with three to six stirringpaddles and a variable-speed motor drive. The stirring machine is mounted on top of afloc illuminator, as is shown in Figure 3-18. The illuminator provides the light needed fora clear visual inspection of the floc produced during the jar test. Use of the jar test appara-tus is discussed in chapter 5 and also in another book in this series, Water Treatment.
Membrane Filter ApparatusA membrane filter is capable of filtering particles as small as 0.45 μm from water. A typi-cal apparatus consists of three basic parts: a filter holder base, a membrane filter, and a fil-ter funnel. The apparatus fits on top of a vacuum filter flask (Figure 3-19) or on a suitablydesigned vacuum manifold (Figure 3-20). The filter holder base is available in stainlesssteel, fritted glass, and plastic. The funnel is available in heat-resistant glass, plastic, orstainless steel. In addition to use in coliform analysis, the membrane filter apparatus canbe used in many tests requiring preparation by filtration.
FIGURE 3-18 Jar test apparatus Courtesy of Phipps & Bird
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OvensAn oven is required in a laboratory primarily to dry, burn, or sterilize. The most com-monly used ovens are utility ovens, muffle furnaces, and autoclaves.
Utility ovensUtility ovens (Figure 3-21) typically have an operating temperature range of 30°C–350°C.They can be of two types: gravity convection or forced air. In addition, some models areconstructed so that a vacuum can be applied. These ovens are used for drying samples andlabware at 105°C prior to weighing, or for sterilizing labware at 170°C for use in bacterio-logical testing.
Muffle furnacesMuffle furnaces (Figure 3-22) are high-temperature ovens used to ignite or burn solids.The weight of the volatile materials is found by subtracting the weight after ignition fromthe weight before ignition. Muffle furnaces are lined with firebrick and generally havesmall ignition chambers. They usually operate at temperatures near 600°C.
AutoclavesAutoclaves (Figure 3-23) are pressure cookers that are used to sterilize such items as glass-ware, sample bottles, membrane filter equipment, culture media, and contaminated discardmaterials. They sterilize by exposing the material to steam at 121°C and 15 psi (100 kPa) fora specified period of time. Exposure time varies with the kind of material to be sterilized.The use of presterilized disposable equipment may eliminate the need for an autoclave inthe preparation of the equipment for use, but some sort of sterilization process is needed toproperly dispose of biologically contaminated materials.
FIGURE 3-19 Membrane filter apparatus on top of a vacuum filter flask
300200100
MembraneFilter
Filter Funnel
Filter HolderBase
Vacuum Flask
Hose Connectedto a Vacuum
Source
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FIGURE 3-20 Membrane filter apparatus on top of a vacuum manifold
FIGURE 3-21 Utility oven Courtesy of Barnstead International
FIGURE 3-22 Muffle furnace Courtesy of Barnstead International
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RefrigeratorsA refrigerator is required in a laboratory to store chemical solutions and to preserve samples.A wide range of laboratory refrigerators is available, but standard domestic refrigerators aresufficient for most facilities. For bacteriological sample storage, a refrigerator capable ofmaintaining a temperature between 1°C and 5°C is required.
Chemical solutions and samples should not be stored in the same refrigerator. Sepa-rate storage minimizes the chance of cross contamination. A separate refrigerator shouldbe used for the storage of microbiological samples and reagents since the fumes of somechemicals may be harmful to the organisms. Food should never be kept in a refrigeratorthat is used for sample or chemical storage.
SAFETY EQUIPMENTChemical burns and fires are common laboratory hazards. Every laboratory should beequipped to protect laboratory personnel from chemical burns and to extinguish smallfires.
Eye ProtectionThe eyes are some of the most vulnerable parts of the human body and should be pro-tected. Safety goggles or protective face shields should be worn when there is danger offlying particles or spattering liquids. Although prescription glasses can be purchased withshatterproof lenses, they do not surround the eyes with a tight-fitting covering to protect
FIGURE 3-23 Autoclave Courtesy of Brinkmann Instruments, Inc.
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against splashes, nor do regular safety glasses. Chemical splash goggles (Figure 3-24) andfull-face shields (Figure 3-25) are specifically designed to reduce the chance of liquidsreaching the eye. Also, the lens material is resistant to impact and penetration. Both typesof eye protectors can be worn over normal prescription glasses.
Contact lenses can increase eye injury from chemical splashes. It is recommended thatthey not be worn in laboratories or chemical storage areas, since the fumes from the chem-icals can react with the moisture in the eyes and be trapped behind the lenses. The result ischemical burns to the cornea.
FIGURE 3-24 Safety goggles Courtesy of Bel-Art Products, Inc.
FIGURE 3-25 Full-face shield Courtesy of Thomas Scientific, Inc.
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An eyewash should be available in every laboratory. When a highly alkaline or acidicchemical touches the eyes or skin, deterioration begins immediately; the longer the periodof contact, the greater the damage that will occur. The eyewash quickly floods the eye withwater. Eyewashes can consist of bottles with an eye cup or spray nozzle designed to floodthe eye (Figure 3-26) or they can be permanent plumbing fixtures similar to drinkingfountains (Figure 3-27).
Deluge/Safety ShowersDeluge/safety showers deliver a torrent of water in a uniform pattern to wash a person’sbody as completely and as rapidly as possible. As shown in Figure 3-28, a freestandingdeluge/safety shower can be placed in a convenient, easy-to-reach location in the labora-tory. The shower should have a large, easy-to-grab pull-chain ring or a paddle valve. Oncethe shower is turned on, it should remain on until deliberately turned off. These can alsobe attached to an alarm visual light and horn or bell to notify others that assistance maybe needed.
FIGURE 3-26 Eyewash bottles Courtesy of Bel-Art Products, Inc.
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FIGURE 3-27 Eyewash apparatus similar to a drinking fountain
FIGURE 3-28 Deluge shower
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Fire ExtinguishersQuick use of a fire extinguisher can prevent a small laboratory fire from becoming a largeone. Every laboratory should have at least one all-purpose fire extinguisher (Figure 3-29)capable of putting out small fires. The type of extinguisher chosen for the laboratoryshould match the types of chemicals available that could burn, that is, organics, certainmetals, and so on. Laboratories should also be equipped with a fire blanket. The blanket’smajor purpose is to extinguish burning clothing, but it can also be used to smother liquidfires in small open containers. The blanket (Figure 3-30) is usually stored in a containermounted on a wall or column and is arranged in the container so that it can easily bepulled out. The fire extinguisher and fire blanket can extinguish most small fires thatmight commonly occur in the laboratory. The condition of the extinguisher and blanketshould be checked monthly and recorded.
Water Stills and DeionizersTwo types of high-purity water are commonly used in most laboratories:
1. Distilled water2. Deionized water
Water stillsA water distillation unit (still) produces the distilled water needed for many laboratory testsand for rinsing labware prior to use. Stills like the one shown in Figure 3-31 produce distilledwater from common tap water by evaporation and condensation. Distilled water is free ofdissolved minerals, uncombined gases, and all types of organic and inorganic nonvolatilecontaminants. Stills can be portable or fixed and are generally made of glass for laboratoryuse. They can be heated by gas, electricity, or steam. Laboratory-size stills generally have anoutput capacity from about 0.3 to 5 gph (1.1 to 18.9 L/hr).
FIGURE 3-29 Fire extinguisher FIGURE 3-30 Fire blanket
EMERGENCYFIRE
BLANKET
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DeionizersA deionizer removes all dissolved inorganic material (ions) from water using special ion-exchange resins. Organic matter, chlorine, uncombined gases, and fine particulates are notremoved unless the unit is equipped with special cartridges for their removal. As is shownin Figure 3-32, deionizers are available in simple cartridge form for direct connection toany laboratory water faucet. The units continue to produce deionized water until the resinbecomes exhausted. Exhaustion of the deionizer is signaled by a change in resin color orby a light or meter provided with the unit. When exhausted, the old cartridge is removedand a new one inserted in its place. Deionizers should be sized for the requirements of thefacility and the anticipated usage.
Deionized water can be used in place of distilled water for most general laboratorypurposes, including the preparation of solutions and washing of precipitates, extraction,and rinsing of glassware. Deionized water cannot be substituted for distilled water whereorganic impurities will interfere with an analytical method unless the unit is also equippedwith a cartridge that removes organic chemicals.
SUPPORT EQUIPMENTA well-equipped laboratory includes a variety of support equipment used for various tests.
AspiratorsAn aspirator is a T-shaped plumbing fixture with a Venturi throat that connects to a waterfaucet and is used to create a vacuum. A typical glass aspirator is shown in Figure 3-33.
FIGURE 3-31 Water stillCourtesy of Barnstead International
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Metal or plastic units are best for use in a sink. When the faucet is turned on, water flowsdown the vertical leg of the aspirator, creating a negative pressure (vacuum) in the hori-zontal stem. When it is connected to a vacuum filter flask, an aspirator produces the vac-uum needed for many laboratory filtering operations.
Aspirators can create a cross-connection and a potential hazard to the laboratorywater supply. The faucet used to connect an aspirator should be provided with an atmo-spheric vacuum breaker.
Hot PlatesHot plates are widely used in laboratories for heating solutions. Hot plates usually have atemperature range of 100°C–500°C. The heating surface is smooth for easy cleaning and is
FIGURE 3-32 Deionizer Courtesy of Barnstead International
FIGURE 3-33 Aspirator
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made of a corrosion-resistant material such as glass, ceramic, or aluminum. A hot plate witha built-in stirring unit is illustrated in Figure 3-34. Hot plates come in various sizes thataccommodate only one piece of glassware up to about a dozen. The larger units are usefulwhen warming large numbers of flasks for tests such as threshold odor determinations.
BurnersA gas (Bunsen) burner is a convenient high-temperature heating device used in any labora-tory served by natural gas or equipped with bottled gas (Figure 3-35). Burners are providedwith adjustable air intake shutters for proper mixing of air and gas.
FiltersThree types of filters commonly used in laboratories today are filter paper, glass-fiber fil-ters, and membrane filters.
FIGURE 3-34 Hot plate with built-in stirring unitCourtesy of Corning Life Sciences
FIGURE 3-35 Gas burner
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Filter PaperFilters made of porous paper are used to clarify solutions, collect particulates, and sepa-rate solids from liquids. The paper’s pore size is between 5 and 10 μm, and the filters areavailable in diameters ranging from 4.25 to 50 cm.
Glass-fiber filtersFilters made of uniform fine glass fibers are used to filter fine particulates, bacteria, andalgae under a high rate of flow. Pore size varies from 0.7 to 2.7 μm, and diameters from15 to 261 cm are available.
Membrane filtersFilters made of cellulose acetate create membranes with precise pore sizes ranging from0.2 to 5.0 μm. They are available in diameters from 13 to 142 mm. They have many uses inthe laboratory; however, the main use is for bacterial testing. Those used in bacterial test-ing typically have a pore size of 0.45 μm.
Magnetic StirrersMagnetic stirrers are used to stir solutions continuously for long periods of time. They aresimilar in appearance to laboratory hot plates, having a corrosion-resistant top of alumi-num, glass, or ceramic material. Beneath the top is a variable-speed motor that drives arotating magnetic field. This magnetic field spins a magnetized, plastic or Teflon-coatedstirring bar that is placed in the liquid to be stirred. Units driven by water or air are usedwhen the chemicals to be mixed should be kept from possible sparks or heat buildup, bothof which can occur with electric motors. Combination magnetic stirrer–hot plate unitscontain separately controlled heating elements and stirring mechanisms. The units canfunction as heaters, stirrers, or both.
Vacuum PumpsVacuum pumps are commonly used in laboratories to aid in filtration. A large laboratorymay have a large vacuum pump connected by pipes to taps in different areas of the labo-ratory. Smaller laboratories find small, portable pressure-and-vacuum pumps suitable(Figure 3-36). These portable units typically use a 1/8 -hp to 1/3 -hp electric motor and canproduce vacuums of as much as 28 in. (94 kPa) of mercury and pressures of as much as50 psig (350 kPa, gauge). The attached filters, shown in Figure 3-36, help to provide oil-free output air. When using the vacuum pump with water samples, always place a largevessel between the filter apparatus and the vacuum pump to act as a water trap and keepwater out of the pump.
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ANALYTICAL LABORATORY INSTRUMENTSMany sensitive instruments are required in a water laboratory to measure various param-eters. Some of the more common ones are described in the following paragraphs.
BalancesThe balance is a precise instrument used to measure mass. The pan balance or rough bal-ance weighs loads as much as approximately 2 kg. Pan balances are available in single-and double-pan models. All balances should be protected from dust and dirt, kept on avibration-free surface, and protected from drafts. The balance should also be checked forlevelness before each use, since tilting can affect the loading on the knife edges, forcecoils, or balance points. Spills on the balance should be cleaned up immediately so thatthe instrument does not corrode.
Single-pan balancesTo use the single-pan balance, the item to be weighed is placed on the pan and the coun-terweights, located on the three horizontal arms (beams), are adjusted. The indicatorarrow on the far right end of the three beams will show when the counterweights equal theweight of the item. The weight reading is obtained by adding the amount of weight oneach of the three beams.
FIGURE 3-36 Pressure-and-vacuum pump Courtesy of Gast Manufacturing, Inc.
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Double-pan balancesThe double-pan balance has the same capability as the single-pan balance, but the proce-dure is more time consuming. “Standard weights” must be placed on the right-hand panuntil the two pans can be balanced by sliding a weight across a beam. Some of these bal-ances even have a calibrated mini-chain to add weight in the decimal level for measuringvery small masses. The weight of the substance is then found by adding all of the weighingcomponents together—standard pan weights, beam rider, and chain links.
Analytical balancesAnalytical balances are far more sensitive and precise than pan balances and can detect achange in weight of as little as ±0.0001 g (0.1 mg). The most convenient and practicalanalytical balance used in today’s laboratory is the automatic single-pan balance(Figure 3-37). The word automatic refers to the built-in standard weights, which areplaced in operation quickly and “automatically” by simply turning a knob. The finalweight is easily read from a display. This system simplifies the weighing procedure andminimizes errors in recording weights. The rapidity of the weighing is an important fea-ture of the analytical balance because items being weighed can pick up moisture from theair, causing a slow weight gain.
Digital balancesTop-loading digital balances (Figure 3-38) are now replacing the older types of balancesbecause of their improved accuracy and speed of operation.
Locations for balancesA balance must be located on a solid, level surface for it to function properly. Metal coun-ters, for example, are not suitable because of the flexibility and potential movement of themetal. Vibrations from machinery operating nearby or from an unstable floor can betransmitted through the table to the balance, causing an inaccurate reading. The vibra-tions from machinery can be greatly reduced if a properly constructed table is located onan unyielding floor.
Most laboratories use solid-marble balance tables like the one shown in Figure 3-39.These tables reduce the transmission of vibrations from the floor and remain level. Theyshould be placed on concrete floors if possible, near a bearing wall if above ground level,and in an environment with relatively constant temperature and humidity and with nosunlight.
MetersA variety of specialized meters are used in water treatment plant laboratories for measur-ing water quality characteristics.
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FIGURE 3-37 Automatic single-pan analytical balance Courtesy of Thomas Scientific, Inc.
FIGURE 3-38 Top-loading portable electronic balance Courtesy of Ohaus Corporation (Scout® Pro)
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ColorimetersThe concentrations of many chemicals can be determined by measuring the intensity ofcolor in a chemical reaction. Colorimetric measurements may be made using a wide vari-ety of equipment, including standard color-comparison tubes, photoelectric colorimeters,and spectral photometers (Figure 3-40). Each has its place and its particular applicationin the laboratory.
Color comparators with permanent color standards for specific parameters can bepurchased for laboratory and field use. There are two types of comparators. The disk typeconsists of a wheel of small colored glasses. The slide type consists of liquid standards andglass ampules. Comparators give rapid, fairly acceptable, consistent results. The mostcommon comparators are the chlorine residual test kit, used by most water utilities, andthe chlorine–pH test kit, used for swimming pools. These comparator-type kits may beused for process control, but not for reportable readings to the primacy agency. The cur-rent regulations require that any measurement taken for compliance testing must be madewith an electronic colorimeter or photometer, whether it is for chlorine residual, pH, orany other parameter.
Electrical conductivity metersA common way of obtaining a quick estimate of the concentration of dissolved solids inwater is to measure the electrical conductivity (EC) of the water. The EC meter actuallymeasures the electrical resistance of the water between two electrodes suspended in thesample. The instrument readout is in microhms per centimeter at 25°C. In general, every10 units of EC represents 6 to 7 mg/L of dissolved solids.
FIGURE 3-39 Marble balance table Courtesy of Thomas Scientific, Inc.
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PhotometersThe photometer is an electronic device that performs the same function as a colorimeter orcolor comparator. Photometers are far more accurate and precise than visual colorimeters.A photometer can measure small differences in color intensities not easily seen by thehuman eye. Other advantages over visual colorimeters include freedom from variable lightconditions and elimination of errors because of color blindness or color bias of the analyst.
The photometer is versatile, easy to use, and relatively inexpensive. US EnvironmentalProtection Agency (USEPA) drinking water regulations require the use of photometers intesting for nitrate, arsenic, fluoride, and chlorine residual.
A basic photometer, such as the one in Figure 3-41, has five main components:
1. White-light source2. Wavelength control unit3. Sample compartment4. Detector5. Meter
The white light passes through the wavelength control unit (a simple colored filter, adiffraction grating, or a prism) to produce a single-color light (light of a specific wave-length). The single-color light then passes through the treated sample, which is containedin a glass tube (cuvette) in the sample compartment. The amount of light that passes
FIGURE 3-40 Pocket ColorimeterCourtesy of Hach Company
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through the sample is sensed by the detector and indicated on the graduated scale or digi-tal meter. The measurement can be expressed in terms of percent transmittance or interms of absorbance. Finally, the concentration of the measured constituent is found froma previously prepared calibration curve (Figure 3-42). Such a curve must be prepared foreach constituent to be measured. At regular intervals, or any time results appear suspect, acomplete new set of standards should be prepared to check the calibration curve.
There are two basic types of photometers, the electrophotometer and the spectrophoto-meter. The basic difference between the two is the method used to produce the single-color light.
Electrophotometers. An electrophotometer uses a simple colored-glass filter. A spe-cific filter color is required for each constituent measured. Electrophotometers are gener-ally used for just a few difficult constituent determinations. A newer type of thisinstrument, used for individual tests such as chlorine residual and nitrates, employs a cali-brated diode that produces the proper wavelength of light used in the measurement of thereagent-reacted sample. Also available are on-line photometers that allow for the continu-ous monitoring of various parameters, most commonly chlorine residuals. Current regula-tions require their installation at various locations.
Spectrophotometers. A spectrophotometer uses either a diffraction grating or a prism tocontrol the light color. When the angle of the grating or the prism is adjusted, different lightcolors (different wavelengths of light) can be selected. Thus, one adjustable grating or prismprovides a continuous spectrum of color selections. A spectrophotometer is particularly usefulwhen a wide variety of constituents is being measured. Its versatility allows convenient selec-tion of the best light color for any test.
A special type of spectrophotometer, the atomic absorption spectrophotometer (AAunit), is used for analyses of most heavy metals in water. It is a sophisticated and expensiveanalytical tool that must be operated by specially trained laboratory technicians.
FIGURE 3-41 Photometer Courtesy of Bacharach, Inc., Photo by Dick Brehl
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In the AA procedure, the sample is vaporized either in a flame or graphite furnace. Aspecial light source, from a specific type of hollow-cathode lamp or an electrodeless dis-charge lamp, emits light at a wavelength that is characteristic of the element being mea-sured. The amount of light absorbed by the vapor is measured. This absorbance is directlyproportional to the concentration of the element in the sample.
Another method being used to measure metals is inductively coupled plasma–massspectrometry (ICP–MS). Instruments provide a reading for many metals at the same timefrom one sample injected into an argon plasma flame. This procedure creates ions of themetals that are separated in the mass spectrometer and provides a determination of theconcentration of the metal present in the sample.
pH metersA pH meter is a sensitive voltmeter that measures the pH (acidity or basicity) of samples.Meters having graduated scales indicate pH units from 0 to 14. More sophisticated metershave expanded scales that allow more precise pH measurement within a narrower rangeand a millivolt scale that allows measurement of specific ions, such as fluoride. Manyinstrument types are available; a typical meter with digital readout is shown in Figure 3-43.
One or two electrodes are supplied with the meter. One electrode, a standard calomelreference type, develops a constant voltage to be compared against the changing voltageof the second. The voltage of the second electrode, a glass type, changes as the pHchanges. The second electrode is designed so that a change of one pH unit produces a volt-age change of 59.1 mV at 25°C. In some units, the two electrodes are mounted in a singleunit called a combined or combination electrode. There may also be an additional probe fortemperature compensation as changes in temperature can affect the pH results. This typeof pH system is falling out of use with the use of the combination electrodes mentioned inthe next paragraph.
On-line pH meters that contain combination electrodes with temperature compensa-tion are in common use. They are used to monitor pH at various stages of the treatment
FIGURE 3-42 Calibration curve
1009080
6050
70
4030
20
100 0.1 0.2 0.3 0.4 0.5 0.6
Sample Concentration, mg/L
Tran
smis
sion
,%
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train so that pH levels can be monitored and if needed maintained within certain optimalranges.
Specific-ion metersThe concentration of a specific constituent in water, such as fluoride, can be measuredwith a specific-ion meter. The complete unit consists of a millivolt meter and interchange-able electrodes. Each electrode is selectively sensitive to one particular constituent of thewater, and each specific-ion test requires a different electrode. There are currently morethan 20 selective electrodes, including electrodes that will measure chloride, copper, hard-ness, fluoride, sodium, and chlorine.
In general, most specific-ion electrodes are only useful for applications in which manyconsecutive tests must be made on similar samples. Frequent calibrations may be neces-sary, often rendering the testing more time consuming than testing by other methods.Also, the electrodes are subject to interference. The fluoride electrode is an exception; theresults it obtains are excellent.
The specific-ion meter (Figure 3-44) resembles a pH meter, with two major differences:the addition of a millivolt scale on the meter face and the provision for use of selective-ionelectrodes. Often a pH meter is purchased with a millivolt scale so that it can also be usedas a specific-ion meter. A specific-ion meter may read concentration directly or it may readin millivolts, in which case concentration is determined by using a standard curve. When ameter with millivolt readings is being used, a standard curve to convert from millivolts toconcentration must be developed. This conversion is made by measuring several samples ofknown concentration and plotting the results.
There are on-line versions of these probes available that provide feedback for certainparameters of interest in the treatment plant. These on-line probes are especially useful ifyou are feeding fluoride to monitor for the proper feed on a continuous basis.
FIGURE 3-43 Typical pH meter Courtesy of Thermo Electron Corp.
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TurbidimetersA turbidimeter measures the clarity of water by measuring the amount of light impeded byor scattered by the suspended particles in the water sample. USEPA drinking water regula-tions approve only the nephelometric method for measuring turbidity. Therefore, althoughthere are other methods, the nephelometric method will be the only one discussed.
Nephelometric turbidimeters are very similar to photometers in both appearance andperformance. The turbidimeter consists of the following major components:
• Light source• Focusing device• Sample compartment• Detector (photomultiplier tube)• Meter
As shown by Figure 3-45, light passes through a focusing device into the sample com-partment and through the sample. The light is reflected by the individual particles thatcause turbidity. Some of that reflected light strikes a detector, such as a phototube, located90 degrees off the main light path. The detector measures the amount of light reaching it.Particles that do not reflect light do not produce a turbidity reading. The meter indicatesthe corresponding turbidity in nephelometric turbidity units (ntu).
Nephelometric turbidimeters are quick and relatively easy to standardize and operate.Most meters have readouts that indicate turbidity values directly. The meters usually haveseveral scale ranges; the most common ones are 0–0.2, 0–1, 0–10, 0–100, and 0–1,000 ntu.
Because all communities using surface water sources are required to test their treatedwater daily for turbidity, the turbidimeter is a necessity at every surface water plant. It isone of the most commonly used instruments.
FIGURE 3-44 Specific ion meter Courtesy of Thermo Electron Corp.
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WATER LABORATORY EQUIPMENT AND INSTRUMENTS 103
A variation of the basic turbidimeter is the continuous–monitoring on-line type. Insteadof a sample compartment, this type has a flow-through chamber in which turbidity is contin-uously measured (Figure 3-46). A complete online installation typically consists of the flow-through nephelometric sensor, a meter-type turbidity indicator, and a chart recorder orconnection to a data recorder. Such installations are used to monitor the turbidity of rawwater, in-process water, and finished water. The regulations for surface water plants now callfor one of these units to be mounted on each filter effluent and the readings to be recorded atleast every 15 minutes during the filter’s operation. Specific regulations as to the turbiditymust be adhered to, and the instruments must be carefully maintained and calibrated.
FIGURE 3-45 Path of light through a nephelometric turbidimeter
FIGURE 3-46 Nephelometric turbidimeter with flow-through chamber Courtesy of Hach Company
Phototube
Slit
LightSource
Sample
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104 WATER QUALITY
MicroscopesA microscope magnifies extremely small objects so they can be seen and studied. Thenaked eye can see objects as small as 40 μm across, about half the diameter of a humanhair. Through very powerful magnification, the microscope extends human vision into theincredibly small worlds of algae and bacteria. Two types of microscopes can be found inwell-equipped water laboratories; one is the binocular wide-field dissecting microscopeand the second is the compound microscope.
The wide-field dissecting microscope is the simplest optical microscope. Basically, it isa hands-free magnifying glass that can magnify an object up to 20 times. This measure-ment is abbreviated 20×, meaning the diameter of the image is 20 times greater than thediameter of the object. This type of microscope is used in membrane filtration techniquefor bacteria to count the colonies on the membrane. It can also be used in customer ser-vice work when a sample collected from a customer has particles that may need to be iden-tified. These can come equipped with a light source for added illumination.
The other type of microscope is the compound microscope, which uses two or morelenses. A compound microscope consists of five basic parts (Figure 3-47):
1. Stand.2. Movable stage.3. Head, including oculars or eyepiece lenses (a one-ocular head is called a monocular; a
two-ocular head, a binocular; a triocular has an additional “eyepiece” designed formounting a camera or digital feed to a computer or screen).
4. Objective nosepiece, a revolving set of lenses (the selection of different objectives givesdifferent magnifications).
5. Illuminator (light source) and condenser lens used to focus light onto the object beingviewed.
Typically, the compound microscope magnifies as much as 1,000×. As is shown inTable 3-1, the magnifying power of a compound microscope depends on the combinedmagnification of the eyepiece (ocular) and the objective lenses. For example, a 20× objec-tive lens combined with a 10× eyepiece produces a 200× magnification (20 × 10 = 200).
The compound microscope may be one of the most important tools in the water qual-ity laboratory. It is used for counting and identifying the microscopic plant and animal lifetypically found in water, including color-, taste-, and odor-causing algae and certain typesof bacteria (e.g., iron bacteria) related to water quality.
The newer models can be attached to a camera or even a computer to record the areaor field the microbiologist is looking at on the slide. These capabilities are valuable whentraining others to use the microscope. In addition, when a question comes up, a picturecan be forwarded to others for assistance in identifying organisms.
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WATER LABORATORY EQUIPMENT AND INSTRUMENTS 105
Measurement of Organic ChemicalsAnalytical instruments that measure trace levels of organic contaminants are relativelysophisticated and somewhat expensive. Many large water utility laboratories use gas chro-matographs, or gas chromatography–mass spectrometers (GC–MS).
Gas chromatographs are essentially sophisticated distillation units; they consistmainly of ovens, columns, and detectors. The organic compounds in the sample arevaporized, moved through the columns by an inert gas, separated, and then moved to a
FIGURE 3-47 Compound microscopeCourtesy of Olympus America, Inc
TABLE 3-1 Optical microscope magnification
Overall Magnification
Type of Objective 10× Ocular 15× Ocular
16 mm (10× or low power) 100× 150×
8 mm (20× or medium power) 200× 300×
4 mm (43× or high power) 430× 645×
1.8 mm (90× or oil immersion) 900× 1,350×
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106 WATER QUALITY
detector. The results are displayed on a chart called a chromatograph. The separation ofthe various compounds takes place in these special columns by chemical characteristicsof the compound.
A mass spectrophotometer is nothing more than a special detector on the end of a gaschromatograph. However, it has the ability to identify many organic compounds by theirmass (weight) and fragmentation pattern. A computer is usually an integral part of a gaschromatograph or GC–MS unit. It can help identify compounds through its library ofinformation on compound characteristics.
Many steps including extraction, drying, and concentrating a sample may be necessaryto prepare a sample for injection into these sophisticated instruments. You may see termsdescribing “cold-vapor extractions” or “solid-phase microextraction” (SPME); both areprocesses that remove the organics from the water and concentrate them in a solvent suitablefor injection into the instrument.
SELECTED SUPPLEMENTARY READINGSBurlingame, G.A. and M.S. Pryor. 2009. A Tale of Two Utilities: Comparing Diverse
Distribution Systems. Opflow, 35(3):14–17.
Manual M12, Simplified Procedures for Water Examination. 2002. Denver, CO:American Water Works Association.
Manual of Instruction for Water Treatment Plant Operators. 1991. Albany, N.Y.: NewYork State Department of Health.
Manual of Water Utility Operations. 8th ed. 1988. Austin, Texas: Texas Water UtilitiesAssociation.
Posavec, S. 2002. Understanding Coliform Testing Methods. Opflow, 20(6):14–18.
Schreppel, C. 2010. Plant Performance Picture Emerges with Instrumentation. Opflow,36(1):22–24.
Standard Methods for the Examination of Water and Wastewater. 21st ed. 2005.Washington, D.C.: American Public Health Association, American Water WorksAssociation, and Water Environment Federation.
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107
C H A P T E R 4
Microbiological Contaminants
HISTORYMore than 2,500 years ago, Hippocrates, who is called the father of medicine, theorizedthat many diseases were caused by drinking water, but he was unable to explain why. Overthe ages, great epidemics caused by contaminated drinking water periodically killed largesegments of populations. It was not until the nineteenth century that the germ theory wasdeveloped by researchers, such as Friedrich Henle, Robert Koch, and Louis Pasteur.
Practically all pathogenic organisms that can be carried by water originate from theintestinal tracts of warm-blooded animals, particularly humans (fecal-oral route). Somewaterborne diseases can be spread by “carriers”—individuals in whose bodies the diseaseis active but who show few or no symptoms. One famous carrier was Mary Mallon, awoman who became known as Typhoid Mary. In the 1930s, she infected perhaps as manyas 1,000 people in the United States with typhoid fever but never showed severe symptomsof the deadly disease herself.
The disease-causing organisms that are considered the principal sources of potentialwaterborne diseases are listed in Table 4-1. Most of these diseases can also be transmittedby other means, such as through food (contaminated water used to wash or prepare) orbody contact (improper washing of hands and surfaces after handling contaminatedobjects, in day-care centers, hospitals, and so on). Many of the diseases that caused tre-mendous loss of life just 100 years ago have now been virtually eradicated in most areas ofthe world through a combination of improved sanitation and the use of new medications
In 1990, US Environmental Protection Agency’s (USEPA’s) Science Advisory Board(SAB), an independent panel of experts established by Congress, cited drinking water con-tamination as one of the most important environmental risks and indicated that disease-causing microbial contaminants (that is, bacteria, protozoa, and viruses) are probably thegreatest remaining health risk-management challenge for drinking water suppliers(USEPA/SAB 1990). Information on the number of waterborne disease outbreaks from theUS Centers for Disease Control and Prevention (CDC) underscores this concern. CDCindicates that, between 1980 and 1996, 401 waterborne disease outbreaks were reported. Ofthe more than 750,000 associated cases of disease reported during this period, 403,000 werefrom the Milwaukee, Wisconsin, Cryptosporidium incident of 1993. During this period, anumber of agents were implicated as the cause, including protozoa, viruses, and bacteria. In2003 and 2004, 30 waterborne “mixed-agent” outbreaks were reported; approximately2,700 persons became ill, and four people died. With the 9/11/2001 terrorist attacks andadded security monitoring the CDC is now keeping track of waterborne illnesses as “mixedcauses” to include all sources of illness, including chemicals microbial agents and othersources such as radiologicals.
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108 WATER QUALITY
Waterborne diseases are usually described as acute, which means that the symptomsare sudden but in healthy people only last a short time. Most waterborne pathogens causegastrointestinal illness with diarrhea, abdominal discomfort, nausea, vomiting, and othersymptoms. Some waterborne pathogens can be associated with more serious disorderssuch as hepatitis, gastric cancer, peptic ulcers, myocarditis, swollen lymph glands, meningi-tis, encephalitis, and many other diseases.
Protozoa, bacteria, and viruses are microorganisms. Microorganisms are organismstoo small to be seen by the naked eye and can only be seen with a microscope.
TABLE 4-1 Waterborne diseases
Waterborne Illness
Causative Organism
Source of Organism in Water
Symptom/Outcome
Gastroenteritis Salmonella (bacteria)Clampyobacter
(bacteria)
Animal or human feces
Acute diarrhea and vomiting
Typhoid Salmonella typhi (bacteria)
Human feces Inflamed intestine, enlarged spleen, high temperature—fatal
Dysentery Shigella Human feces Diarrhea—rarely fatal
Cholera Vibrio cholerae (bacteria)
Human feces Vomiting, severe diarrhea, rapid dehydration, min-eral loss—high mortality
Infectious hepatitis
Virus (Hepatitis A) Human feces, shell-fish grown in pol-luted waters
Yellowed skin, enlarged liver, abdominal pain; lasts as long as 4 months—low mortality
Amoebic dysentery
Entamoeba histolytica (protozoa)
Human feces, sewage Mild diarrhea, chronic dysentery
Giardiasis Giardia lamblia (protozoa)
Animal feces sewage Diarrhea, cramps, nau-sea, general weakness; lasts 1–30 weeks—not fatal
Cryptosporidiosis Cryptosporidium Human and animal feces
Diarrhea, abdominal pain, vomiting, low-grade fever
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MICROBIOLOGICAL CONTAMINANTS 109
The pathogens that are still of some concern as sources of waterborne disease are dis-cussed in the following sections.
BacteriaBacteria are single-cell microorganisms that are smaller than parasites but larger andmore complex than viruses. They multiply by binary fission—that is, by replicating theirsingle strand of DNA and dividing in half. The more common shapes are spheres, rod-shaped, spiral, and branching threads, or filamentous. Bacteria range in diameter from 0.5to 1 micrometers (μm) and in length from 2 to 4 μm. Some have flagella, a taillike struc-ture for movement; others are nonmotile.
Pathogenic bacteria of interest in drinking water are Salmonella, pathogenic Escheri-chia coli (E. coli), Shigella, Legionella, and Campylobacter.
Salmonella typhi causes typhoid fever, which has been virtually eradicated in the U.S.due to sanitation. Enteropathogenic E. coli causes gastroenteritis in humans, most notablydiarrhea, but certain pathogens of the family such as E. coli O157:H7 can cause kidneyfailure and death in certain susceptible individuals. Shigella causes bacillary dysentery thatis usually not life threatening. Campylobacter infections result in diarrhea and vomiting.Legionella causes pneumonialike symptoms; infection of susceptible hosts occurs throughinhalation of the bacteria from aerosols. It is often found in cooling towers and colonizesplumbing systems. An example of the aerosol route Legionella takes when infectinghumans is through the mist from showerheads.
Opportunistic pathogens are not normally a danger to persons in good health, butthey can cause sickness or death in those who are in a weakened condition. Particularly atrisk are newborns, the elderly, those who are immunocompromised, and persons whoalready have a serious disease.
Included among the opportunistic bacteria are Pseudomonas, Aeromonas hydrophila,Edwardsiella tarda, Flavobacterium, Klebsiella, Enterobacter, Serratia, Proteus, Providen-cia, Citrobacter, and Acinetobacter. These organisms are prevalent in the environment,and with modern multibarrier treatment techniques—including improved coagulationcontrol, improvements in the type and construction of filters including membranes, addi-tional types and combinations of disinfection, and improved monitoring of the treatmentprocess for particulate removal—the probability that they will be removed from the watersupply is greatly increased.
VirusesViruses are complex molecules that typically contain a protein coat surrounding a DNA orribonucleic acid (RNA) core of genetic material. Viruses have no independent metabolism anddepend on living cells for reproduction. They range in diameter from 10 to 25 nanometers (nm),which is smaller than can be seen with an optical microscope.
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110 WATER QUALITY
Viruses can survive for varying periods of time in the environment outside of ahuman’s or an animal’s body, remaining alive in the presence of heat, drying, and chemicalagents. Some viruses are much more resistant than bacteria to chlorine in water, and theadenoviruses are very resistant to ultraviolet light (UV).
Some types of viruses have caused acute epidemics of gastroenteritis. The waterbornehepatitis A virus (HAV) is the source of some of the most serious health problems. HAVcauses infectious hepatitis, which can result in serious liver damage or death. The CDCdocumented 23 outbreaks of disease caused by HAV between 1971 and 1985. Newly rec-ognized viruses include noroviruses that cause rapid-onset diarrhea and vomiting; chil-dren are particularly susceptible to the viruses.
ProtozoaThe protozoan parasites of concern in drinking water are Giardia lamblia and Cryptosprid-ium. Both parasites reproduce in the intestine of a susceptible host (humans or animals)and shed environmentally resistant cysts (Giardia) or oocysts (Cryptosporidium) in theirfeces. The cysts and oocysts can survive for long periods of time in the environment andare fairly resistant to disinfection. Chlorine inactivates Giardia cysts, and the contact timesestablished in the Surface Water Treatment Rule are based on inactivation of this parasite.Cryptosporidium is resistant to some chemical disinfectants but is very susceptible to UV,which has become a widely accepted treatment for surface waters in the past decade forthis reason.
Giardia lambliaGiardiasis is the most frequently diagnosed waterborne disease in the United States.Symptoms include skin rash, flulike problems, diarrhea, fatigue, and severe cramps. Thesymptoms may last anywhere from a few days to months. Sometimes there are periods ofremission when there are no symptoms, and then the illness recurs. The protozoanattaches itself to the upper intestinal tract and produces cysts, which are shed in thefeces. Giardia cysts are relatively large, ranging between 8 and 18 μm in length andbetween 5 and 15 μm in width.
One of the major reasons that giardiasis continues to be a problem is that the cystssurvive well under adverse conditions. They are highly resistant to chlorine and can live incold water for months. Three of the major hosts for Giardia cysts are humans, beaver, andmuskrat. Although water can be a major means of transmitting the disease, the largestpercentage of recorded cases is caused by person-to-person contact.
CryptosporidiumCryptosporidium is a parasite that has caused several outbreaks of cryptosporidiosis andposes serious health risks. Sixteen species are currently recognized. Cryptosporidium par-vum is found in humans and animals, while C. hominis is found only in humans.
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MICROBIOLOGICAL CONTAMINANTS 111
In healthy individuals, cryptosporidiosis is an infection that usually causes 7 to 14days of diarrhea with possibly a low-grade fever, nausea, and abdominal cramps. Theeffects on immunocompromised individuals can be life threatening. No antibiotic treat-ment currently exists for cryptosporidiosis.
Oocysts averaging about 4 to 6 μm in size may be found in all types of water, includinguntreated surface water and filtered swimming-pool water. Outbreaks can be caused bycontamination of food and of water in swimming pools and sprinklers. The 1993 outbreakin Milwaukee resulted in the deaths of 50 individuals, most of whom died of other diseasesrelated to their immunocompromised conditions or who were already suffering from anunderlying illness. An estimated 403,000 illnesses were attributed to this event—abouttwo-thirds of the population served by the water system (Milwaukee’s population at thetime was about 617,000).
PreventionCryptosporidium infections are contracted by the ingestion of oocysts, and therefore effec-tive control measures must aim to reduce or prevent oocyst transmission. Cryptosporidiumoocysts are resistant to the disinfectants used in most water treatment plants. Conven-tional water treatment is effective at oocyst removal through coagulation and filtration.Currently, UV light is the most effective treatment for inactivating oocysts.
INDICATOR ORGANISMSThe tests required to detect specific pathogens are still considered time intensive andexpensive, so it is impractical for water systems to routinely test for specific pathogens. Amore practical approach is to examine the water for indicator organisms specifically asso-ciated with contamination. An indicator organism essentially provides evidence of fecalcontamination from humans or warm-blooded animals. The criteria for an ideal indicatororganism are that it should
• always be present in contaminated water;• always be absent when fecal contamination is not present;• generally survive longer in water than pathogens;• be easy to identify.
The coliform group of bacteria has been used for 100 years as an indicator of drinkingwater quality. These bacteria are generally not pathogenic, yet they may be present whenpathogens are present.
Coliform bacteria are easily detected in the laboratory. As a rule, where coliforms arefound in water, it is assumed that pathogens may also be present, making the water bacte-riologically unsafe to drink. If coliform bacteria are absent, the water is assumed safe.
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112 WATER QUALITY
Many methods exist for determining the presence of coliform bacteria in a water sam-ple, including the multiple-tube fermentation (MTF) method, the presence–absence (P–A)method, the MMO–MUG method, and the membrane filter (MF) method. Detaileddescriptions of the analytical procedures for these tests can be found in the latest editionof Standard Methods for the Examination of Water and Wastewater.
Coliform AnalysesThe detection of coliform bacteria in a water sample by any of the four analytical tech-niques is a warning of possible contamination. One positive test does not conclusivelyprove contamination, however, and additional tests must be conducted. Samples are oftencontaminated by improper sampling technique, improperly sterilized bottles, and labora-tory error. Regulatory agencies recognize this fact, and drinking water regulations requirecheck or repeat sampling after findings that show a positive test for coliform in a sample.Drinking water regulations and maximum contaminant levels for coliform bacteria arediscussed in chapter 1.
SamplingSterile containers must be used for all samples collected for bacteriological analysis. Thesame sampling procedures should be used for coliform analysis and heterotrophic platecount (HPC) analysis (refer to chapter 2). See Table 4-2.
Test MethodsThe MTF and P–A tests are designed on the principle that coliform bacteria produce gasfrom the fermentation of lactose within 24 to 48 hours when incubated at 35°C. Althoughthe bacteria themselves cannot be seen, their presence is signified by the gas that is formedand trapped in an inverted vial in the fermentation tube.
Multiple-tube fermentation methodThe MTF test (Figure 4-1) progresses through three distinct steps:
1. Presumptive test2. Confirmed test3. Completed test
Presumptive test. The presumptive test is the first step of the analysis. Samples arenormally pipetted into tubes containing a culture medium (lauryl tryptose broth [LTB])with inverted filed vials containing the media in the tubes. The samples are incubated for24 hours and then checked to see if gas has formed in the inner vial and cloudiness has
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MICROBIOLOGICAL CONTAMINANTS 113
(continued)
TABLE 4-2 Total coliform sampling requirements, according to population served
Population Served Minimum Number of Routine Samples per Month*
15 to 1,000† 1‡
1,001 to 2,500 2
2,501 to 3,300 3
3,301 to 4,100 4
4,101 to 4,900 5
4,901 to 5,800 6
5,801 to 6,700 7
6,701 to 7,600 8
7,601 to 8,500 9
8,501 to 12,900 10
12,901 to 17,200 15
17,201 to 21,500 20
21,501 to 25,000 25
25,001 to 33,000 30
33,001 to 41,000 40
41,001 to 50,000 50
50,001 to 59,000 60
59,001 to 70,000 70
70,001 to 83,000 80
83,001 to 96,000 90
96,001 to 130,000 100
130,001 to 220,000 120
220,001 to 320,000 150
320,001 to 450,000 180
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114 WATER QUALITY
developed in the broth. If neither is the case, they are incubated for 24 hours more andchecked again.
If coliform bacteria are present in the water, the gas they produce will begin to form abubble in each inverted vial within the 48-hour period; this is called a positive sample orreported as presence. If no gas forms, the sample is called negative or reported as absence.If gas is produced after either the 24-hour or the 48-hour incubation period, the samplemust undergo the confirmed test.
450,001 to 600,000 210
600,001 to 780,000 240
780,001 to 970,000 270
970,001 to 1,230,000 300
1,230,001 to 1,520,000 330
1,520,001 to 1,850,000 360
1,850,001 to 2,270,000 390
2,270,001 to 3,020,000 420
3,020,001 to 3,960,000 450
3,960,001 or more 480
Source: Water Quality and Treatment (1999).
* In lieu of the frequency specified in this table, a noncommunity water system using groundwater and serving 1,000 persons or fewer may monitor at a lesser frequency specified by the state until a sanitary survey is con-ducted and the state reviews the results. Thereafter, noncommunity water systems using groundwater and serv-ing 1,000 persons or fewer must monitor in each calendar quarter during which the system provides water to the public, unless the state determines that some other frequency is more appropriate and notifies the system in writing. Five years after promulgation of the Total Coliform Rule (TCR), noncommunity water systems using groundwater and serving 1,000 persons or fewer must monitor at least once per year.
† Includes public water systems that have at least 15 service connections but serve fewer than 25 persons.‡ For a community water system serving 25 to 1,000 persons, the state may reduce this sampling frequency if a
sanitary survey conducted in the last 5 years indicates that the water system is supplied solely by a protected groundwater source and is free of sanitary defects. However, in no case may the state reduce the sampling fre-quency to less than once per quarter.
TABLE 4-2 Total coliform sampling requirements, according to population served (Continued)
Population Served Minimum Number of Routine Samples per Month*
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MICROBIOLOGICAL CONTAMINANTS 115
Confirmed test. The confirmed test is more selective for coliform bacteria. This testincreases the likelihood that positive results obtained in the presumptive test are caused bycoliform bacteria and not other kinds of bacteria. Cultures from the positive samples inthe presumptive test are transferred to brilliant green lactose bile (BGB) broth and incu-bated. If no gas has been produced after 48 hours of incubation, the test is negative and nocoliform bacteria are present. If gas is produced, the test is positive, indicating the pres-ence of coliform bacteria.
Bacteriological testing of most public water supplies stops after the confirmed test.This is the minimum testing that all samples must undergo when the MTF method isused. To check its procedures, the laboratory should conduct the completed test on atleast 10 percent of the positive tubes from the confirmed test.
Completed test. The completed test is used to definitely establish the presence of coli-form bacteria for quality control purposes. A sample from the positive confirmed test isplaced on an eosin methylene blue (EMB) agar plate and incubated. A coliform colonywill form on each EMB plate.
A small portion of the coliform colony is transferred to a growth medium andincubated for 18 to 24 hours. A second portion is transferred to an LTB and incubatedfor 24 to 48 hours. The completed test is positive if (1) gas is produced in the LTB and(2) red-stained, nonsporeforming, rod-shaped bacteria are found. If no gas is produced inthe LTB or if red-stained, chainlike cocci or blue-stained, rod-shaped bacteria are foundon the agar, the test is negative. Figure 4-2 provides a summary of the MTF method. (Thebacteria are not visible to the human eye. A microscope is needed to read the plates anddetermine the bacteria type.)
FIGURE 4-1 Typical multiple-tube fermentation setup Source: Opflow
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116 WATER QUALITY
FIGURE 4-2 Summary of the multiple-tube fermentation method
A. Presumptive test
B. Confirmed test
C. Completed test
Add water samples to five tubes containing inverted vials andLTB and incubate 24 hours.
Gas produced.Positive presumptive test.
No gas produced.Incubate an additional 24 hours.
Gas produced.Positive presumptive test.
No gas produced.Negative presumptive test.
Coliform group absent.
Transfer portion of positive culture to BGB broth and incubate 48 hours.
Gas produced.Positive confirmed test.Coliform group present.
No gas produced.Coliform group absent.
Transfer portion of positive culture to EMB agar plate and incubate 24 hours.
Transfer small amount ofcoliform colony from EMB plate
to nutrient agar slant and toLTB and incubate both.
No gas produced.Red-stained cocci or blue-stained,
rod-shaped bacteria found.Negative completed test.
Gas produced.Red-stained, nonsporeforming,
rod-shaped bacteria found.Positive completed test.
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MICROBIOLOGICAL CONTAMINANTS 117
Presence–absence testThe P–A test is a simple modification of the MTF method. It is intended for use on routinesamples collected from a distribution system or water treatment plant. A 100-mL portionof the sample is inoculated into a 250-mL milk dilution bottle containing special P–Amedia and a small inverted tube. The sample is then incubated at 35°C for 24 and 48 hours.
The presence of total coliforms is indicated by the purple P–A medium turning yellow(indicating acid production) and by the formation of gas in the medium. All yellow andgas-producing samples from this presumptive stage must then be confirmed as describedfor the MTF-confirmed step using BGB tubes. Gas production indicates the presence oftotal coliforms and must be reported as a positive sample (presence) in the monthly reportto the primacy agency.
Samples confirmed for total coliforms must also be analyzed for either fecal coliformsor E. coli. A check or repeat sample must also be collected and analyzed. If the check/repeatsample is positive this can result in an acute violation of the Total Coliform Rule (TCR) andmust be reported to the primacy agency within 24 hours after results become known.
Fecal coliform procedure. If the MTF or P–A method is being used, as the presump-tive positive samples are being inoculated into the BGB broth, 0.1 mL of the presumptivebroth is also transferred into an EC broth tube. (The actual name of the broth is EC and isa test for Escherichia coli.) If the membrane filter method is used, bacterial growth istransferred into an EC tube. This tube is then incubated for 24 hours in a water bath at44.5°C. The presence of gas in the tube confirms the presence of fecal coliforms.
E. coli procedure. The presence of E. coli can be determined using the MUG test dis-cussed in the next section. A 0.l-mL portion of the presumptive media or a swab is used totransfer a sample from a membrane filter into an EC–MUG tube. A tube that fluorescesunder a long-wave UV light is confirmation for E. coli.
MMO–MUG techniqueThe MMO–MUG technique was approved by USEPA shortly after promulgation of theTCR. MMO and MUG are acronyms for the constituents in the medium used in the tests.MMO represents minimal media with ONPG (ONPG stands for ortho-nitrophenyl-beta-D-galactopyranoside). E. coli produce a specific enzyme that reacts with ONPG to give a yel-low color. MUG stands for 4-methylumbelliferyl-beta-D-glucuronide. Only E. coli producean enzyme that reacts with MUG. Therefore, a medium containing MMO and MUG can beused to identify both total coliforms and E. coli in a single-sample inoculation.
Two procedures may be used. In the ten-tube procedure, ten tubes are purchased withthe medium already in them. A 10-mL portion of sample is transferred into each tube andincubated at 35°C for 24 hours. In the P–A procedure, the medium is purchased in vials.The medium is transferred into a bottle containing 100 mL of sample, is mixed, and isincubated as in the ten-tube procedure. If total coliforms are present in either procedure,
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the medium will turn yellow. If E. coli are present, the medium will also fluoresce blueunder a UV light.
Membrane filter methodThe MF method of coliform testing begins with the filtering of 100 mL of sample under avacuum through a membrane filter. The filter is then placed in a sterile container/petridish (Figure 4-3) and incubated in contact with a selective culture medium.
A coliform bacteria colony will develop at each point on the filter where a viable coli-form bacterium was left during filtration. After a 24-hour incubation period, the numberof colonies is counted (Figure 4-4).
A typical coliform colony on M-Endo media is pink to dark red with a distinctivegreen metallic surface sheen. All organisms producing such colonies within 24 hours areconsidered presumptive coliforms. For confirmation, representative colonies are inocu-lated into LTB and BGB broth.
The USEPA is revising the TCR, and the proposed new rule will use E. coli as theindicator for fecal contamination. Total coliform will be used as an indicator that theremay be a problem in the system and will trigger a system investigation.
Alternate methodsOther methods for coliform and E. coli detection are being developed using a combina-tion of enzymes, ß-glucuronidase, and ß-galactosidase in combination with ONPG andMUG. In tests that are positive for coliform, a yellow substance is produced that fluo-resces at 366 nm UV after a 24±2-hr incubation at 35.0°C ± 0.5°C. There are variousmethods of determination, from just adding the water sample to a test bottle containingthe media and incubating, to pouring the water sample into a tray containing the detec-tion media with volumetric cells for counting, similar to the MPN method. The methodhas been approved for use by USEPA but may need to be confirmed with the drinkingwater primacy agency for your area.
HETEROTROPHIC PLATE COUNT (HPC) PROCEDUREThe HPC procedure is a way to estimate the population of bacteria in water. The testdetermines the total number of bacteria in a sample that grows under specific conditionsin a selected medium.
Uses of the HPC ProcedureNo single food supply, incubation temperature, and moisture condition suits every type ofbacteria being tested for, so a standardized procedure must be used to obtain consistentand comparable results. The procedure therefore generally permits only a fraction of thetotal population to be cultured. Often the number of HPC colonies is orders of magnitudelower than the total population present.
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Plate-count tests are sensitive to changes in raw-water quality and are useful for judg-ing the efficiency of various treatment processes in removing bacteria. For example, if aplate count is higher after filtration than before filtration, there may be bacterial growth onor in the filters. The problem would probably not show up during routine coliform analysis.
It is also common for water leaving a treatment plant to have a low bacterial populationbut for the population to have greatly increased by the time the water reaches the consumer.
FIGURE 4-3 Placement of membrane on pad soaked with culture medium
FIGURE 4-4 Membrane filter after incubation with positive growth colonies
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This occurrence is caused by bacterial aftergrowth (regrowth)—bacteria reproducing in thedistribution system. Standard plate-count determinations may indicate whether this prob-lem exists. Bacterial aftergrowth can generally result from water becoming stagnant in thedead ends in the system, inadequate chlorination, or recontamination of the water afterchlorination.
Performing the HPC ProcedureThe HPC is performed by placing diluted water samples on plate-count agar. The samples areincubated for 48 to 72 hours. Bacteria occur singly, in pairs, in chains, and in clusters. The bac-teria colonies that grow on the agar are counted using colony-counting equipment. Detailedprocedures are described in the latest edition of Standard Methods. These procedures must beclosely followed to provide reliable data for water quality control measurements.
Properly treated water should have an HPC of less than 500 colonies per milliliter.Higher counts indicate an operational problem that should be investigated.
SELECTED SUPPLEMENTARY READINGSCraun, M.F., Craun, G.F., Calderon, R.L., and Beach, M.J. 2006. Waterborne
Outbreaks Reported in the United States. Jour. Water and Health, 04 Suppl 2. London:IWA Publishing.
Edberg, S.C., F. Ludwig, and D.B. Smith. 1991. The Colilert® System for Total Coliformsand Escherichia coli. Denver, CO: American Water Works Association ResearchFoundation and American Water Works Association.
Embrey, M.A., R.T. Parkin, J.M. Balbus, and George Washington University School ofPublic Health and Health Services. 2002. Handbook of CCL Microbes in DrinkingWater. Denver, CO: American Water Works Association.
Hill, D.R. 2006. Basic Microbiology for Drinking Water Personnel, 2nd Edition. Denver,CO: American Water Works Association.
LeChevallier, M.W., W.D. Norton, R.G. Lee, and J.B. Rose. 1991. Giardia andCryptosporidium in Water Supplies. Denver, CO: American Water Works AssociationResearch Foundation and American Water Works Association.
Leland, D.E., J. McAnulty, W. Keene, and G. Stevens. 1993. A CryptosporidiosisOutbreak in a Filtered-Water Supply. Jour. AWWA, 85(5):34.
Manual M12, Simplified Procedures for Water Examination. 2001. Denver, CO:American Water Works Association.
Manual M48, Waterborne Pathogens. 2006. Denver, CO: American Water WorksAssociation.
Manual M57, Algae. 2010. Denver, CO: American Water Works Association.
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MICROBIOLOGICAL CONTAMINANTS 121
Manual of Instruction for Water Treatment Plant Operators. 1991. Albany, N.Y.: NewYork State Department of Health.
Manual of Water Utility Operations. 8th ed. 1988. Austin, Texas: Texas Water UtilitiesAssociation.
Miller, K.J. 1994. Protecting Customers From Cryptosporidium. Jour. AWWA, 86(12):8.
Moore, A.C., B.L. Herwaldt, G.F. Craun, R.L. Calderon, A.K. Highsmith, and D.D.Juranek. 1994. Waterborne Disease in the United States, 1991 and 1992. Jour. AWWA,86(2):87.
Pontius, F.W. 1990. Rule Changes Way Systems Will Look at Coliform. Opflow,16(12):1.
———. 1993. Protecting the Public Against Cryptosporidium. Jour. AWWA, 85(8):18.
Rochelle, P.and J. Clancey. 2006. The Evolution of Microbiology in the Drinking WaterIndustry. Journ. AWWA, 98(3):163–191.
Standard Methods for the Examination of Water and Wastewater. 21st ed. 2005.Washington, D.C.: American Public Health Association, American Water WorksAssociation, and Water Environment Federation.
Water Quality and Treatment. 6th ed. 2010. New York: McGraw-Hill and AmericanWater Works Association (available from AWWA).
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123
C H A P T E R 5
Physical and Aggregate Properties of Water
This chapter describes the physical properties of water. It coincides with Standard Meth-ods for the Examination of Water and Wastewater, 21st edition (2005).
Physical testing of drinking water measures the physical properties of the water as dis-tinguished from chemical or biological contaminants.
Several physical tests are either required by regulations or necessary for control of thewater treatment processes. Water systems using surface water sources perform physicaltests frequently because of changing water quality. Groundwater quality generally fluctu-ates slowly or infrequently and so most physical, chemical and microbiological testing ofgroundwater is performed periodically but less frequently. Tests ensure that optimumtreatment is provided and that the finished water meets state and federal standards.
ACIDITYThe definition of acidity is base neutralizing power. There are two types of acidity: phenol-phthalein acidity (CO2 acidity), which is prevalent above pH 4.3, and mineral acid acidity,which tends to be in the lower pH ranges. Phosphoric acid, hydrochloric acid, and sulfuricacid are all mineral acids. Acidity and alkalinity exist in the water at the normal pH levelsfound in water since the existence of basic molecules such as negative ions does notexclude the existence of the acid type of molecule positive ions.
Methods of MeasurementMineral acids are measured by titration to a pH of 4.3 using methyl orange as an indicator(orange on the alkaline side to salmon pink on the acid side). Mineral acidity plus aciditycaused by weak acids (e.g., carbonic acid) is measured by titration of the sample to thephenolphthalein end point (pH 8.3). This is called total acidity or phenolphthalein acidity.Phenolphthalein is colorless at a pH less than 8.3 and pink or red above pH 8.3.
To a theoretical chemist, a pH of 7 is considered neutral. To a water chemist, though,who wants to know how much free or combined CO2 is present and how much total alka-linity is present, a pH of 7 has less meaning. The water chemist is interested in what makesup the pH and how much buffering exists.
SignificanceAcidity plays a more important role in industrial water applications, especially in neutral-ization reactions. In drinking water, acids are associated with corrosive environments.
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Chemical reaction rates are influenced by acidity. Acids are used in the regeneration ofion-exchange systems. They are also used to lower the pH of water treated by nanofiltra-tion and reverse osmosis membranes.
ALKALINITYThe definition of alkalinity is acid neutralizing power (see Table 5-1).
TypesPhenolphthalein alkalinity (P alkalinity) has a pH end point of 8.3. Methyl orange ortotal alkalinity (MO alkalinity) has a pH end point of 4.3 and is directly related to theamount of hydroxide (OH), carbonate (CO3), or bicarbonate (HCO3) alkalinity present.
More specifically, when water samples have a pH above 10, hydroxide anions (OH–)are the primary constituent of the pH-causing ions. Titration with strong acid is completeat the phenolphthalein end point (8.3). Hydroxide alkalinity is equal to phenolphthaleinalkalinity.
In water samples with a pH of 8.3 or higher, carbonate ions are the primary alkalinitycomponent. Titration to phenolphthalein end point is exactly one-half of total titration topH 4.3. Carbonate alkalinity equals total alkalinity.
If only hydroxide-carbonate is present, water samples will have a high pH, usually wellabove 10. Titration from pH 8.3 to 4.3 represents one-half of carbonate alkalinity.
If only carbonate-bicarbonate is present, water samples will have a pH greater than8.3 and less than 11. Titration to pH 8.3 represents one-half of carbonate alkalinity.
If only bicarbonate is present, water samples will have a pH of 8.3 or less (usuallyless). Bicarbonate alkalinity equals total alkalinity.
TABLE 5-1 Alkalinity relationships
Result of TitrationHydroxide Alkalinity
Carbonate Alkalinity
Bicarbonate Alkalinity
P* = 0
* P = phenolphthalein
0 0 MO
P < ½ MO†
† MO = methyl orange
0 2P MO – 2P
P = ½ MO 0 2P 0
P > ½ MO 2P – MO 2 (MO – P) 0
P – MO MO 0 0
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CALCIUM CARBONATE STABILITYThe principal scale-forming substance in water is calcium carbonate (CaCO3). Water isconsidered stable when it will neither dissolve nor deposit calcium carbonate. This point isreferred to as the calcium carbonate stability or equilibrium point. The reactions andbehavior of calcium carbonate and calcium bicarbonate are therefore important in watersupplies. The actual amount of calcium carbonate that will remain in solution in waterdepends on several characteristics of the water: calcium content, alkalinity, pH, tempera-ture, and total dissolved solids (TDS).
SignificanceScale formation can cause serious problems in water distribution mains and householdplumbing systems by restricting flow, plugging valves, and fouling water heaters and boil-ers. Corrosion can cause premature pipe or equipment failure. Public health and aestheticproblems can also result if water is corrosive, because pipe materials (e.g., lead, cadmium,and iron) will dissolve into the water.
Several methods can be used to determine the calcium carbonate stability of water. Apopular method is the Langelier Saturation Index (LSI). The LSI is equal to the measuredpH (of the water) minus the pHs (saturation). The pHs is the theoretical pH at which cal-cium carbonate will neither dissolve into nor precipitate from water. Water at the pHs isconsidered stable. Therefore, if pH – pHs = 0, the water is in equilibrium and will neitherdissolve calcium carbonate nor deposit it on the pipes.
If pH – pHs > 0 (positive value), the water is not in equilibrium and will tend todeposit calcium carbonate on mains and other piping surfaces. If pH – pHs < 0 (negativevalue), the water is also not in equilibrium and will tend to dissolve the calcium carbonateit contacts; no coating will be deposited on the distribution pipes, and if the pipes are notprotected, they may corrode.
The calcium carbonate stability of water is maintained in the distribution system byadjusting the LSI of the water to a slightly positive value so that a slight deposit of cal-cium carbonate will be maintained on pipe walls. Adjustment is usually made by addinglime, soda ash, or caustic soda.
Indices other than the LSI use alkalinity as part of the equation or method to deter-mine the stability of the water, especially its corrosiveness. One is the marble test, in whichcalcium carbonate (limestone) CaCO3 is dissolved in the water sample and the initial alka-linity is compared with the final alkalinity. The Ryzner Index is used to perform a similarcalculation to the LSI; it indicates the corrosiveness of the water compared to the pHs.
Alkalinity is also important in determining how effectively the water reacts with coag-ulants for plant treatment. The alkalinity ions acts as a “reservoir” of molecules that areavailable to react with coagulants or other chemicals such as disinfectant to reduce the pHchange to the water which these chemical may affect, this effect is known as the “bufferingcapacity.” Low-alkalinity waters have less buffering capacity and can produce less floc or
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weak floc without the addition of chemicals to increase the buffering capacity of thewater. This is because many coagulants are acidic compounds.
SamplingIf calcium carbonate stability maintenance is used for corrosion control, finished water atthe treatment plant and in the distribution system should be evaluated routinely for cal-cium carbonate stability. Evaluation is particularly important when treatment plant unitprocesses or chemical doses are changed. If the LSI indicates unfavorable conditions, pro-cess adjustments should be made. It is very important to remember that the LSI is only anindicator of stability; it is not an exact measure of corrosivity or of calcium carbonatedeposition. The LSI is developed from results of alkalinity, pH, temperature, calcium con-tent, and TDS (dissolved residue) monitoring.
Methods of DeterminationIf the temperature, TDS, calcium content, and alkalinity of the water are known, the pHscan be calculated. The following equation may be used:
pHs = A + B – log (Ca+2) – log (alkalinity)
In the equation, A and B are constants, and calcium and alkalinity values are expressed interms of milligrams per liter as calcium carbonate equivalents.Table 5-2 and 5-3 are usedto determine the values of the constants and logarithms.
The actual pH of the water is measured directly with a pH meter, and the LSI is calcu-lated using the formula LSI = pH – pHs.
Example:A sample of water has the following characteristics:
Determine the saturation index, LSI:
An LSI of +1.4 indicates that this water is scale forming.
Ca+2 = 300 mg/L as CaCO3
Alkalinity = 200 mg/L as CaCO3
Temperature = 16°CDissolved residue = 600 mg/LpH = 8.7
pHs = A + B – log (Ca+2) – log (alkalinity)pHs = 2.20 + 9.88 – 2.48 – 2.30
pHs = 7.3
LSI = 8.7 – 7.3 = +1.4
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COAGULANT EFFECTIVENESSThe removal of suspended solids from surface water is necessary both to make the wateraesthetically pleasing to customers and to assist in the elimination of pathogenic organ-isms. The Surface Water Treatment Rule (SWTR), the Total Coliform Rule (TCR), andthe Disinfectants Disinfection By-Products Rule (D/DBP) require more complete removalof turbidity and dissolved organics than was previously practiced by most water systems.This requirement in turn demands more efficient coagulation, flocculation, and sedimen-tation. Effective coagulation is also a tool in removing organic chemical precursors fromthe raw water.
TABLE 5-2 Constant A as a function of water temperature
Water Temperature, °C A
0 2.60
4 2.50
8 2.40
12 2.30
16 2.20
20 2.10
TABLE 5-3 Constant B as function of total dissolved solids
Total Dissolved Solids, mg/L B
0 9.70
100 9.77
200 9.83
400 9.86
800 9.89
1,000 9.90
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128 WATER QUALITY
SignificanceCoagulation and flocculation involve the addition of chemical coagulants such as aluminumsulfate, ferric chloride, or polyelectrolytes to raw water to hasten the settling of suspendedmatter. Plant operation is most efficient when the lowest turbidity is obtained in finishedwater with the lowest cost for coagulant chemicals. Several laboratory tests can provide theinformation necessary to accomplish this goal. These tests allow operators to select optimalchemical dosages in the laboratory rather than using trial and error in the plant.
The tests can also be used to check the adequacy of flash mixing or flocculation mix-ing in the plant. Test results may indicate when to improve or modify flash mixers andflocculation basins to obtain more efficient operation. These treatment processes areexplained in detail in Water Treatment, another text in this series.
When coagulants are evaluated, the goal is to identify the one coagulant (or combina-tion of coagulant and coagulant aids) that will produce low turbidity with the least expen-sive dose of chemicals. Chemical prices must also be evaluated, because a low dose of anexpensive chemical may be more cost effective than a high dose of an inexpensive chemi-cal. One must also consider the cost and ease of disposal of the coagulant and the contam-inants removed in the process.
SamplingWhere the samples are collected for analysis depends on the procedure being used and theinformation desired from the test. The tests should be conducted whenever there is a sig-nificant change in water quality or when other conditions may require a change in coagu-lant dose.
Methods of DeterminationThe following methods are commonly used to determine optimum coagulant effectiveness:
• Jar test• Zeta potential detector• Streaming current detector (SCD)• Particle counting
Jar testThe jar test is readily available to most operators and has been commonly used for manyyears. There is no standard procedure for conducting the jar test, nor is there standard testequipment that must be used. A typical procedure for conducting a jar test is provided inAmerican Water Works Association (AWWA) Manual M12, Simplified Procedures forWater Examination.
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Briefly, the procedure is to collect a sample of the raw water and add progressivelylarger doses of the coagulant chemical being tested to several jars of the sample. The testshould be run as quickly as possible after the sample has been collected because a change inwater temperature can have a significant effect on the results. Actual plant conditions offlash-mixing speed and time, flocculation time, and settling time are then simulated in thejars.
Visual observation of the floc and turbidity readings of the settled water in the jarsprovide the data necessary to make determinations. The types of equipment available forperforming jar tests ranges from simple hand-shaken jars to computer-controlled testingdevices. A motor-driven jar test device is pictured in Figure 3-18 in chapter 3.
Figure 5-1 illustrates typical jar test results from a water supply in which alum is usedas a coagulant. The data show that the benefit of the coagulant decreases with doses largerthan 35 mg/L for turbidity removal. In other words, beyond that dose a very large increasein the amount of chemical is required to produce a small increase in turbidity removal.Therefore, 35 mg/L should be considered the optimal dose for alum alone for the watertested for turbidity removal. Additional coagulant may be required to obtain the neces-sary total organic carbon (TOC) removal as required by the D/DBP.
Zeta potentialCoagulation and flocculation are an electrochemical process in which the electrical resis-tance between the suspended particles (colloids) in the water is lowered to the point thatthey will adhere to each other and settle out as a heavy floc.
FIGURE 5-1 Typical jar test results
30
20
10
Turb
idity
, ntu
0 10 20 30 40 50 60 70
Chemical Dose, mg/L Aluminum Sulfate
Optimum Coagulant Dosage 35 mg/L
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130 WATER QUALITY
In many water plants, technicians use a zeta meter to assist in evaluating the effective-ness of coagulant doses. Zeta potential may be viewed as the electrical charge on a sus-pended particle that allows it to repulse other particles and thus stay suspended. The typeand amount of coagulant added reduces the zeta potential, and a zeta meter measures thispotential. The closer the reading is to zero, the more the particles tend to settle, thus indi-cating more effective coagulation.
Normally, the zeta meter is not an on-line instrument. Samples may be collected atvarious points in the treatment process to determine coagulant effectiveness, or variouscoagulant doses may be tested on the raw water in bench-scale experiments. Trained per-sonnel are necessary to operate the zeta meter and interpret the data it produces.
Streaming current detectorA streaming current detector (SCD; Figure 5-2) is an on-line continuous-monitoringdevice based on the same electromotive principle as is the zeta meter. The detector mea-sures the effectiveness of the coagulant chemical by determining the level of electricalresistance in the treated water after chemical application.
The advantage of having a continuous-monitoring device is that it allows the operatorto evaluate changes in the chemical doses as changes in raw-water quality occur. A majorconcern in installing an SCD is the maintenance (cleaning) of the electrodes and the cali-bration of the meter to ensure accurate readings. Another advantage of the SCD is that itcan be used to automatically control coagulant dose by connecting the output signal fromthe SCD to a coagulant feed pump. Location of the sample point for on-line control iscritical in that, for best results, the sample must be thoroughly mixed and representative ofthe treatment process before it enters the instrument.
FIGURE 5-2 Streaming current monitor with remote sensor Courtesy of Chemtrac Systems, Inc.
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Particle countingInstruments are available that enumerate the concentration of particles in a water supply bysize. (Figure 5-3). These instruments, known as particle counters, combine particle detec-tion technology with electronic counting technology. A sensor detects the particle and con-verts the information to an electronic signal that is used by the electronic counter.
Particle counters and turbidimeters are similar in that both use a fixed light source tointeract with the particles in water. Turbidimeters use light scattering. Particle countersuse the principle of light blocking. As was mentioned in chapter 3, particles that do notreflect light and are not detected by a turbidimeter can be counted by a particle counter.
Particle counters and turbidimeters are different in that particle counters provide aquantitative measurement, and turbidimeters provide a qualitative measurement. Particlesensors count individual particles according to their size; turbidimeters do not. Particlecounters cannot count particles below a given size. Turbidimeters have the ability to detectsmaller particles. Even though the particle counter can tell you the size and number of theparticles, it cannot yet tell you what that object is.
Particle counting has been a technique in use for the past decade or longer for moni-toring filter performance in regard to filter breakthrough and coagulation efficiency, and
FIGURE 5-3 Liquid particle monitor with remote sensor Courtesy of Chemtrac Systems, Inc.
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132 WATER QUALITY
it is useful in monitoring pathogen removal. It is used for membrane filtrations equipmentin combination with the pressure hold test to monitor membrane integrity. As was notedin chapter 4, the sizes of cysts and oocysts of the pathogens Giardia and Cryptosporidiumare in the micrometer range easily detected by the particle counter. Reducing the numberof particles to above the range of 4–5 μm in the finished water should greatly reduce anyoccurrence of these organisms.
As water quality regulations prescribe lower and lower contaminant levels, watertreatment plant operators will increasingly have to depend on sophisticated control tech-niques such as particle counting for process control.
COLORColor in water may result from the presence of minerals, inorganic chemicals, metals (e.g.,iron and manganese), the decomposition of organic matter from soils, aquatic organismsand vegetation. A problem in surface waters, some groundwaters containing iron or man-ganese and dissolved organic matter can also have significant color levels.
Color in water is classified as either true color or apparent color. True color is definedas the color of water from which turbidity has been removed. Apparent color includes truecolor and color caused by suspended matter.
Color in the yellow to brown range is determined by a visual comparison of the sam-ple with either a known colored chemical solution or a calibrated color disk.
The unit of measurement is the color unit. Color units are the estimated color of adiluted sample times 50, divided by the milliliters of sample taken for dilution. For fin-ished waters, some pristine surface water supplies, or groundwater, the sample normallywould not have to be diluted and could be estimated directly without any division. Thus, a50-mL sample with a low color of 1 would have a result of 1 color unit. Color is reportedin whole numbers from 1 to 500. Sample pH is always reported with the color units.
Other colors in the water, such as blue or red, have other causes and are not assigned anumerical value. They may be listed as to their intensity or shade (e.g., light blue, aqua, pink).
SignificanceColor in drinking water should be removed to produce a pleasing, acceptable appearance.The color of a drinking water affects consumers’ acceptance. Consumers expect a color-less product and will reject colored water; they may change to another source of watereven if the other source is less safe. Color may also indicate high levels of organic com-pounds, which may produce high levels of trihalomethanes (THMs) and other DBPs oncontact with chlorine or other disinfectants.
Color data from raw- and finished-water sample points comprise one indicator of theefficiency of the treatment plant’s processes.
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SamplingSamples collected should represent raw water, finished water, and distribution systemwater, and should include water pH at the point of sampling. Sampling in surface watersystems is especially important.
Methods of DeterminationThe platinum–cobalt method is the preferred method for color analysis. It is useful formeasuring color derived from naturally occurring materials, but it is not applicable tocolor measurement of waters containing highly colored industrial wastes.
CONDUCTIVITYConductivity (specific conductance) is a measure of the ability of an aqueous solution tocarry an electric current. This ability depends on the presence of ions; on their total con-centration, mobility, and valence; and on the temperature of measurement. Solutions ofmost inorganic compounds are relatively good conductors. Conversely, molecules oforganic compounds that do not dissociate in aqueous solution conduct a current verypoorly, if at all.
The units for conductivity are the inverse of unit of resistance (ohm) or(1/ohm-m) ormho (pronounced like “Moe”) per centimeter. In Système International (SI) units, con-ductivity is reported as millisiemens per meter (ms/m). To report results in SI units, dividemho/cm by 10.
Conductivity (specific conductance) is a measure of the ionic strength of a solution.Conductivity is a required water quality parameter of the Lead and Copper Rule. Theconductivity of potable waters in the United States ranges from 50 to 1,500 μmhos/cm or(s) (siemens).
SignificanceConductivity is a general parameter that assists the analyst in evaluating many aspects ofwater quality. In the laboratory, conductivity measurements are used to
• establish the degree of mineralization of a water to assess the effect of the total con-centration of ions, which is particularly relevant to corrosion rates;
• evaluate variations in the concentration of dissolved minerals in a water source;• estimate the concentrations of TDS in water supplied to a distribution system or from
points in the system;• approximate the milliequivalents per liter of either cations or anions in a water sample.
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SamplingA 50-mL aliquot of sample for conductivity measurements may be taken from an unpre-served sample collected from a regularly used bacteriological sample point or from a sam-ple collected at the entry point to the distribution system. The sample should be preservedby cooling it to 39°F (4°C) until it is analyzed.
The sample should also be protected from exposure to the atmosphere, since the watercould desorb or adsorb gases (e.g., ammonia and carbon dioxide) that could dissolve in anionic state. This development would affect conductivity.
Methods of DeterminationLaboratories analyzing a sample for conductivity may not have to be certified, but amethod approved by the US Environmental Protection Agency (USEPA) must be used ifthe results are to be reported to the state for the Lead and Copper Rule.
An approved method uses a self-contained conductivity instrument with conductivitycells containing either platinum or nonplatinum electrodes. Procedures for running thetest may be found in Standard Methods or Methods of Chemical Analyses of Water andWastes from USEPA. Conductivity measurements may be taken in the field.
HARDNESSHardness is a measure of the concentration of calcium and magnesium salts, which aregenerally present in water as bicarbonate salts. Water hardness is derived largely from thewater contacting soil and rock formations. Hard waters usually occur where the topsoil isthick and contains minerals and metals that will dissolve and where limestone formationsare present. Soft waters occur where soil is sandy, the topsoil layer is thin, and limestoneformations are sparse or absent. Another mineral in the soil, gypsum or calcium sulfate(CaSO4), can also contribute to hardness.
SignificanceHard and soft waters are both satisfactory for human consumption. However, consumersmay object to hard water because it causes scale to form in household plumbing fixturesand on cooking utensils. Hardness is also a problem for industrial and commercial usersbecause of scale buildup in boilers and other equipment.
According to the National Research Council,(National Academy of Sciences) waterwith <75 mg/L as calcium carbonate (CaCO3) of hardness is considered soft water. Otherorganizations say that water below about 100 mg/L of CaCO3 is soft, between 100 andabout 175 mg/L of CaCO3 is moderately hard, and over 175 mg/L CaCO3 is consideredhard. Water that is most satisfactory for household use contains about 75 to 100 mg/L asCaCO3. Waters with 300 mg/L as CaCO3 are generally considered too hard. When wateris softened in a water treatment plant, it is either partially softened or blended to result in
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a hardness concentration between 75 and 150 mg/L as CaCO3. Waters containing calciumsulfate hardness at these same levels can cause gastric irritation in some individuals untilthey become acclimated. USEPA has a secondary standard of 250 mg/L of sulfate asCaSO4 in drinking water with a TDS of 500 mg/L.
Very soft waters found in some sections of the United States have hardness concentra-tions of 30 mg/L as CaCO3 or less. These waters are generally corrosive and are sometimestreated to increase hardness.
SamplingIf a water treatment plant softens water, hardness analyses of the finished water should beconducted daily to determine whether the desired degree of softening has been achieved.Analyses should be conducted on samples collected immediately after softening andbefore the water enters a clearwell.
Hardness determinations should also be performed on raw-water samples wheneverweather conditions (e.g., spring rains) affect the supply. This sampling will reveal any varia-tion in the hardness of the raw water and will provide advance information for chemical dos-age changes that may be necessary for softening. Even if softening is not practiced, hardnessdeterminations should still be made periodically as a general water quality measurement.
At least 100 mL of sample should be collected in either glass or plastic bottles. Sam-ples should be cooled to 39°F (4°C) and acidified with 0.5 mL/100 mL to a pH of <2 withnitric acid unless they are going to be analyzed immediately. These acidified and cool sam-ples may be stored for 28 days before analysis.
Methods of DeterminationThe ethylenediaminetetraacetic acid (EDTA) titrimetric method is the preferred methodof analysis. It consists of sequestering (tying up) the calcium and magnesium ions bytitrating with an EDTA solution. The sample is titrated in the presence of an indicator.The initial solution is red, and it changes to blue when all the ions have been sequestered.
TASTE AND ODORTastes and odors in water are difficult to measure. They are caused by a variety of sub-stances including organic matter, dissolved gases, and industrial wastes. Odors in watersupplies are most frequently caused by algae or decaying organic matter. The intensityand offensiveness of odors vary with the type of organic matter.
Odors are generally classified as aromatic, fishy, grassy, musty, septic, or medicinal. Indus-trial wastes, such as phenolic or oil waste, are also responsible for some odors in surface waters.
The human sense of smell is much more sensitive than the sense of taste, so odor testsare most commonly run in water treatment plants. The taste test, which classifies tastes assweet, sour, bitter, and salty, can only be run on water known to be safe for drinking; thusits usefulness is limited.
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SignificanceAn odor test can be used to evaluate how well a water treatment plant removes taste- andodor-causing organic materials. The test can also be used to trace the origins of contami-nation in source water. For example, an odor-causing industrial waste discharge might beoccurring upstream from a water treatment plant. Samples can be collected at intervalsupstream until the problem-causing area has been reached. The odors should becomestronger closer to the discharge and should not be evident in samples collected upstreamfrom the discharge. This technique is time consuming; however, it can be conducted bywater plant personnel, and extensive laboratory facilities are not necessary. An odor testcan also be used to detect problems in the distribution system. For example, odors occurin dead-end water mains having a significant bacteriological buildup. A definite chlorineodor can indicate the loss of free chlorine caused by stagnation, slime buildup, and/oranaerobic conditions.
The threshold odor number (TON) is designed to help monitor all types of odors,independent of source. The TON cannot, however, be used to indicate the concentrationof the odor-producing substance, because some substances produce strong odors at lowconcentrations. For example, some chemical wastes, such as phenol in chlorinated water,have been detected by the threshold odor test at a 0.001-mg/L concentration. Other odor-producing substances, such as detergents, may not be detected until the concentration is ashigh as 2.5 mg/L.
An odor with a TON of 3 might be detected by a consumer whose attention is calledto it, but it probably would not be noticed otherwise. If an odor appears gradually, con-sumers will adapt to it, and it will be noticed less than if it appears suddenly. Finished-water quality with a TON above 5 will begin to draw complaints from consumers. When aTON of 3 or more is detected in a finished-water supply, quick action should be taken tosolve the problem.
SamplingWater supplies with seasonal or recurring taste and odor problems should be analyzedregularly and, as problems occur, corrective action should be taken. The tests may be timeconsuming, so it is not generally possible to conduct more than a few tests per day.
Water samples should be taken from raw and finished waters. At least 1,000 mL ofsample should be collected for an odor analysis. Samples should be collected in clean bot-tles that have not been used for any samples that might leave a taste or an odor. The bot-tles should be washed with detergent and rinsed with distilled water and then odor-freewater. Glass sample bottles should be used; plastic containers may add some odor of theirown or an odor from substances that were previously in the container.
Aeration and mixing of the sample should be kept to a minimum before testingbecause air strips or oxidizes odor-producing compounds. An air space should be left atthe top of the bottle so the sample can be thoroughly shaken before testing.
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Odor tests should be run as soon as possible after collection. If the sample must bestored, it should be tightly capped and placed in an odor-free refrigerator. The sampleshould be analyzed no later than 24 hours after collection.
Odor-free water can be generated in the plant or laboratory with an activated carbonfilter purchased and installed on a cold-water tap. Be sure to follow the manufacturer’sinstructions for the use of the filter.
Methods of DeterminationTwo standard methods of quantifying taste and odor in water supplies are in use: thethreshold odor test and the flavor profile analysis (FPA).
Threshold odor testMost tastes and odors are extremely complex, and the best way to detect them is with thehuman sense of smell. A series of sample dilutions are prepared and placed in bottles forobservers to test. Each bottle contains 200 mL of liquid consisting of a mixture of samplewater and odor-free distilled water.
The bottles are arranged so that the observer smells the most dilute samples first andthen from a bottle of completely odor-free water as a reference. Then the next strongestsample is smelled, and again the odor-free water, and the process is continued until anodor is first detected. The TON may be calculated as follows:
Where:Vs = volume of sample, in mLVd = volume of dilution water, in mL
The lowest obtainable TON is 1. If no odor is detected in an undiluted sample, theTON is reported as “no odor observed” and no number is assigned. If an odor is firstdetected in a bottle that has 100 mL of sample diluted to 200 mL with distilled water, theTON is 2. TONs corresponding to various dilutions are shown in Table 5-4.
The threshold odor test is not precise and is based on human judgment. The ability todetect odors varies among individuals, and if very accurate results are desired, a panel offive or more persons is recommended to overcome this variability. Persons performingodor tests should not have colds or allergies that would affect their sense of smell. Theyalso should be nonsmokers and should not use perfumes or aftershaves, which tend to dullthe sense of smell. Plant operators should make odor observations, but because they workin the environment where the odor may exist their sense of smell can become desensitized
V VV
s d
s
+ = TON
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to an odor (anosmia). If they step out of the environment for a short period, their sensitiv-ity may return. All tests must, of course, be conducted in an odor-free atmosphere.
Flavor profile analysisThe FPA was approved by the Standard Methods Committee in 1990 and first appearedas a proposed standard method in the eighteenth edition of Standard Methods.
The FPA differs from the TON in that the samples are not diluted and each individualodorant in the sample is evaluated and numerically rated. FPA can be applied to bothtaste- and odor-causing compounds.
In the procedure, a panel consisting of four to six members and a panel coordinatorconduct each round of testing. Panel members must be selected for their desire to partici-pate, their tested ability to accurately taste and smell samples, and their ability to interactwith other panel members. Dominant personalities are not desirable.
The panel members gather in an odor-free room. The panel coordinator prepares andpresents the samples to the panel members, and they independently write down the taste orodor attributes they have observed. The coordinator writes each observation on a black-board or flip chart and leads a discussion to reach consensus among the panel members.
Panelists are trained in the proper methods of tasting and sniffing samples and aretaught to identify and rate the attributes of both tastes and odors. They must also betrained in how to prepare for a round of testing, i.e., no aftershave or perfume; no smok-ing, gum chewing, or spicy food or drink 1 hour prior to the test; no colds or allergies.
TABLE 5-4 Threshold odor number corresponding to various dilutions
Volume of Sample (mL) Diluted With Odor-Free Water to 200 mL
Threshold Odor Number
0.8 256
1.6 128
3.1 64
6.3 32
12.5 16
25 8
50 4
100 2
200 1
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Standards and references for tastes and odors are commercially available to assist intraining panelists and reaching consensus. For example, to help panel members identifythe four taste attributes, standards can be made from sucrose for sweetness, citric acid forsourness, sodium chloride for saltiness, and coffee for bitterness. Natural material is alsoavailable for panel use; for example, geranium leaves may be used to assist the panel incoming to a consensus on what constitutes a geranium odor in a water sample.
Panel members should follow all the safety precautions mentioned in the methodsince this is the only laboratory test in which the sample is consumed, or at least placeddirectly into the body.
TEMPERATURETemperature is measured on either the Fahrenheit (°F) or the Celsius (°C) scale. Thefreezing point of water is 32°F or 0°C; the boiling point is 212°F or 100°C. Because tem-perature is a factor in computing the Langelier saturation index, it is one of the waterquality parameters required by the Lead and Copper Rule.
SignificanceWater temperature determines, in part, how efficiently certain unit processes operate inthe treatment plant. The rate at which chemicals dissolve and react is somewhat depen-dent on temperature. Cold water generally requires more chemicals for efficient coagula-tion and flocculation to take place. Water with a higher temperature may result in a higherchlorine demand because of increased reactivity and also because there is usually anincreased level of organic matter, such as algae, in the raw water. For surface water plantsin the northern regions, the dropping of the plant effluent water temperature to about the39°F (4°C) point can indicate the start of the cold-weather main breaks.
SamplingTemperature readings must be taken on-site, either directly from the water or from sam-ples immediately after collection. Immediate readings are necessary because the watertemperature will begin to change once the sample is taken.
Methods of DeterminationA laboratory thermometer is used for temperature analysis. The thermometer is left in thewater long enough to get a constant reading, and the measured temperature is expressedto the nearest degree or less depending on the thermometer’s accuracy. Digital battery-operated thermometers are currently available. They have the advantage over glass bulb–type thermometers of being easier to read and less prone to break.
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TOTAL DISSOLVED SOLIDSTotal dissolved solids, also referred to as total filterable residue, in natural waters consistsmainly of carbonates, bicarbonates, chloride, sulfate, calcium, magnesium, sodium, andpotassium. Dissolved metals, dissolved organic matter, and other substances also accountfor a small portion of the dissolved residue in water.
SignificanceDissolved solids in drinking water tend to change the water’s physical and chemicalnature. Distilled or deionized water has a flat taste; most consumers prefer water that con-tains some dissolved solids. Different salts in solution may interact and cause effects thateach salt alone would not cause. The presence of some dissolved compounds or ions (suchas arsenic and mercury) can be harmful in water even where the total solids concentrationis relatively low.
It is generally agreed that the TDS concentration of palatable water should not exceed500 mg/L. Lime softening and ion-exchange facilities both significantly reduce the quan-tity of TDS in finished water.
Many communities in the United States use waters containing 2,000 mg/L or moreTDS because better-quality water is not available. These waters tend to be unpalatable,may not quench thirst, and can have a laxative effect on new or transient users. However,no lasting harmful effects have been reported from such waters. Waters containing morethan 4,000 mg/L TDS are considered unfit for human consumption.
Raw-water source samples can be dipped from just below the surface of the water inthe area of the intake structure. They may be collected in clean wide-mouth glass or plas-tic 1-L containers. Filter effluent samples should be collected from an effluent sample tapor drain line. The sample should be stored in a cooler away from sunlight for transporta-tion to the laboratory.
TURBIDITYTurbidity is an optical property caused by particles suspended in water. These particlescause light rays to be scattered and absorbed rather than transmitted in a straight line,making the water appear cloudy. Turbidity is the measurement of the clarity of a watersample. Waters showing very little light scattering produce low-turbidity measurements;those with a great deal of light scattering have high turbidity. The suspended particlescausing turbidity include organic and inorganic matter and plankton.
Turbidity should not be confused with suspended solids. Turbidity expresses howmuch light is scattered by the sample. Suspended solids measurements express the weightof suspended material in the sample. In most cases, turbidity cannot be correlated to sus-pended solids concentration.
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Interferences with turbidity measurement include color, high turbidity (raw muddywater requires dilution and calculations to obtain a reliable reading), and gas bubbles.Scratched sample cells, condensation, poor calibration, and stray light also interfere.
SignificanceTurbidity is expressed in nephelometric turbidity units (ntu), and a reading in excess of5 ntu is noticeable to consumers. Turbidity is significant in water supplies because it createsa potential public health hazard, unpleasant appearance, and operational difficulties. Themost important of these is the potential public health hazard. The effectiveness of chlorineor other disinfectants depends on the disinfectant making contact with the pathogenicorganisms in the water. Suspended particles in turbid water can shelter microorganismsfrom the disinfectant and allow them to still be viable when they reach the customers.
Turbid water may also contain particles of organic matter that can react with chlorineto form THMs or other DBPs.
Turbidity analyses are also used to evaluate in-plant operations. Turbidity measure-ments taken after settling and before filtration reflect the performance of the coagulation,flocculation, and sedimentation processes. A rise in turbidity after settling indicates that thecoagulant application should be changed and/or that operational corrections must be made.
Settled water before filtration should have a turbidity of less than 10 ntu. If water withhigh turbidity reaches the filter, it will cause high filter head loss and shorten filter runs.Changes in raw-water turbidity usually require that the coagulant dose be changed. Anysignificant change in turbidity within the unit process should be an immediate warningthat operational adjustments are necessary. The operator should set up parameters thatdefine a significant change for a specific unit process and the type of water being treated.For example, if the normal turbidity level doubles, i.e., the raw water goes from 3 to 6 ntufor no apparent reason, operational adjustment is necessary.
Turbidity analyses are also used to monitor finished-water quality for compliancewith state and federal drinking water standards.
SamplingTurbidity analyses are usually conducted on samples collected from raw water, sedimenta-tion basin effluent, filter effluent, and finished water. Figure 5-4 shows some typical tur-bidity sampling points.
At least 100 mL of sample should be collected in a clean glass or polyethylenecontainer. Samples should be shaken and analyzed immediately after collection becausethe level of turbidity can change if the sample is stored. If it is not possible to run a turbid-ity test immediately, the sample should be stored in the dark for no longer than 24 hours.
All filter plants should keep a continuous record of finished-water turbidity. Continuous-reading turbidimeters with recorders installed on the filter-effluent piping will continuouslydetermine, report, and record the quality of the filter effluent. The turbidimeter signal can
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sound alarms to indicate the need to shut down an improperly operating filter. This alarmsystem increases the reliability of the filter operation and is especially important in assuringthe safe operation of pressure filters and high-rate (4 to 6 gpm/ft2 [2.7 to 4.1 mm/sec]) filterplants. It should be noted that the continuous-reading turbidimeter may not match the labo-ratory meter exactly because of differences between the instruments and the methods used.This would be similar to the differences between two cells used to analyze one sample for tur-bidity; slight variations in the manufacturing of the equipment can vary the result.
Methods of DeterminationThe nephelometric turbidimeter measures the scattering of light in nephelometric turbid-ity units. USEPA drinking water regulations specify the use of a nephelometric turbidime-ter for all required monitoring.
Analysis is quick and easy with the nephelometric method. Nephelometry is useful forin-plant monitoring, and results can be compared from plant to plant, which is an advan-tage to operators seeking performance information from other facilities.
Under the requirements of the SWTR, water systems serving a population in excess of500 must perform turbidity monitoring of filtered water at least every 4 hours that the plantis in operation. A system may substitute continuous turbidity monitoring if the equipmentis validated on a regular basis using a procedure approved by the state. The Enhanced Sur-face Water Treatment Rule (ESWTR) requires continuous monitoring of the individual fil-
FIGURE 5-4 Typical turbidity sampling points
Filtration
To Distribution
54
321
Presedimentation Coagulation
FlocculationSedimentation
Source
1. Turbidity of raw water entering the plant.2. Turbidity reduction by presedimentation; helps the operator determine coagulant dose.3. Turbidity removal by coagulation, flocculation, and sedimentation processes; assists the operator in monitoring the efficiency of the process.4. Turbidity after filtration; continuous monitoring of turbidity for each filter monitors for turbidity break-through, which is one of the indicators of the need for filter backwashing.5. Turbidity of all treated water leaving the plant; monitors compliance with drinking water regulations for maximum allowable effluent turbidity.
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PHYSICAL AND AGGREGATE PROPERTIES OF WATER 143
ters in a surface water treatment plant and calls for the turbidity for each filter to berecorded at a minimum of every 15 minutes. Figure 3-46 in chapter 3 is a picture of acontinuous-monitoring turbidimeter.
SELECTED SUPPLEMENTARY READINGSBaker, L.A., P. Westerhoff, and M. Sommerfeld. 2006. Adaptive Management Using
Multiple Barriers To Control Tastes and Odors. Journ. AWWA, 98(6):113–126.
Dietrich, A.M., G.A Burlingame, and R.C. Hoehn. 2003. Strategies for Taste-and-OdorTesting Methods. Opflow, 29(10):10–14.
Gordon, G., W.J. Cooper, R.G. Rice, and G.E. Pacey. 1992. Disinfection ResidualMeasurement Methods. 2nd ed. Denver, CO: American Water Works AssociationResearch Foundation and American Water Works Association.
Jensen, J.N., and J.D. Johnson. 1989. Specificity of the DPD and AmperometricTitration Methods for Free Available Chlorine. Jour. AWWA, 81(12):59.
Manual M12, Simplified Procedures for Water Examination. 2001. Denver, CO:American Water Works Association.
Manual of Water Utility Operations. 8th ed. 1988. Austin, Texas: Texas Water UtilitiesAssociation.
Meng, A.-K., and I.H. Suffet. 1992. Assessing the Quality of Flavor Profile Analyses.Jour. AWWA, 84(6):89.
Pizzi, N.G. 2005. Water Treatment Operator Handbook. Denver, CO: American WaterWorks Association.
Standard Methods for the Examination of Water and Wastewater. 21st ed. 2005.Washington, D.C.: American Public Health Association, American Water WorksAssociation, and Water Environment Federation.
Suffet, I.H., J. Mallevaille, and E. Kawczynski. 1995. Advances in Taste-and-OdorTreatment and Control. Denver, CO: American Water Works Association ResearchFoundation and American Water Works Association.
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145
C H A P T E R 6
Inorganic Chemicals
An inorganic chemical, substance, compound, or contaminant is one not derived fromhydrocarbons. An inorganic contaminant is an inorganic substance regulated by theUSEPA. Inorganic contaminants contained in this list are antimony, asbestos, barium,beryllium, cadmium, chromium (total), copper, cyanide, fluoride, lead, mercury nitrate,nitrite, selenium, thallium, and arsenic. Interestingly, nickel, which was once regulated byUSEPA was remanded; monitoring is still required even though there is currently no MCL.
In drinking water, other inorganic compounds are of interest. These include the diva-lent cations, calcium, magnesium, iron, and manganese.
CARBON DIOXIDECarbon dioxide is a colorless, odorless, noncombustible gas that is found in all naturalwaters. Carbon dioxide in surface waters can originate from the atmosphere, but mostcomes from biological oxidation of organic matter. Biological oxidation is also the pri-mary source of carbon dioxide in groundwater.
SignificanceConsuming excess carbon dioxide in water has not been found to have adverse healtheffects. In fact, carbon dioxide is present in commercial carbonated beverages in concen-trations far greater than those found in natural waters. However, carbon dioxide in waterforms carbonic acid, which can cause corrosion problems. In addition, carbon dioxidevalues must be known to calculate proper lime dosages when softening water. If recarbon-ation is used following lime softening, carbon dioxide values must be determined to con-trol the process. In groundwater, a high level of carbon dioxide reduces the pH andincreases the dissolution rate of metals and minerals from the surrounding earth, iron,manganese, and so on.
SamplingCarbon dioxide analyses should be run on raw and finished water. Special precautionsmust be taken during collection and handling of the sample if the titrimetric method isbeing used. Exposure to the air must be kept to a minimum. Field determination of freecarbon dioxide immediately after sampling is advisable. If field determination is impossi-ble, the sample should be kept cool and the analysis completed as soon as possible.
Samples may be collected in glass or plastic bottles. At least 100 mL of sampleshould be collected. The bottle should be filled to the top with no air space left, and nopreservatives should be added. A piece of tubing from the faucet to the bottom of thecollection vessel should be used to minimize aeration of the sample from splashing or
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bubbling. Fill the container with several volume changes while the tubing is submersed.Slowly remove the tubing from the sample container with the water still flowing to ensurethat the container remains full with no air space.
Methods of DeterminationThe amount of carbon dioxide in water may be determined by using the nomographicmethod or the titrimetric method. To use the nomographic method, the pH, bicarbonatealkalinity, temperature, and total dissolved solids must be known. Results are most accu-rate when the pH and alkalinity are analyzed immediately after sample collection. Thetitration method may be performed potentiometrically or with phenolphthalein indicator.
CHLROINE RESIDUAL AND DEMANDChlorine is usually added to source water as the water enters the treatment plant (prechlo-rination) and again just before it leaves the plant (postchlorination). In the plant, chlorineis also often added at intermediate points during the treatment process. Postchlorination isprimarily administered to provide an excess of chlorine for continued disinfection in thedistribution system. Tests of chlorine levels in the plant and throughout the distributionsystem are necessary to determine that chlorine dosage levels are adequate and to monitorwater quality.
SignificanceDestruction of pathogenic organisms by chlorine is directly related to contact time and theconcentration of the chlorine. High chlorine doses with short contact periods will provideessentially the same results as low doses with long contact periods. Chlorination also oxi-dizes substances such as iron, manganese, and organic compounds, making their removalfrom the water easier.
Successful chlorination requires that enough chlorine be added to complete the disin-fection or oxidation process. However, chlorine must not be added in amounts that arewasteful, creating unnecessarily high operational costs. Determining effective and efficientchlorine dosage levels is the responsibility of the plant operator.
Chlorine ResidualThere are two types of chlorine residual: combined residual and free available residual.The process by which these are formed is illustrated in Figure 6-1.
The first amount of chlorine (for example, 1 mg/L) that is added to raw water is usedin oxidizing reducing compounds such as iron and manganese (from point 1 to point 2 inthe figure). The chlorine oxidizes the iron and manganese and in the process is used up—no residual forms and no disinfection occurs.
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If the initial chlorine dosage used is higher (for example, 2.5 mg/L), the reaction willgo to point 3. Between points 2 and 3, the chlorine reacts with the organic substances andthe ammonia in the water, forming chloroorganics and chloramines. These two productsare called combined chlorine residual. This is a chlorine residual that—because it is com-bined with other chemicals, normally ammonia compounds, in the water—has lost someof its disinfecting strength. Compared with free chlorine, combined chlorine residual is aless effective disinfecting agent. If it is not properly controlled, it may cause tastes andodors characteristic of water in a swimming pool.
As the chlorine dosage is increased further (point 3 to point 4), the chloramines andsome of the chloroorganics are destroyed. This process reduces the combined chlorineresidual until, at point 4, the combined residual reaches its lowest point. Point 4 is calledthe breakpoint. At the breakpoint, the chlorine residual changes from combined to freeavailable.
As the initial chlorine dosage is increased still further (beyond 4 mg/L in this exam-ple), free available chlorine residual is formed—free in the sense that it has not reactedwith anything and available in the sense that it can and will react if necessary. In terms ofdisinfecting power, free available residual is 25 times more powerful than combined resid-ual, and it will not produce the characteristic swimming-pool odor that combined residu-als do. Because free available chlorine residual forms only after the breakpoint, theprocess is called breakpoint chlorination.
The free available chlorine residual at the consumer’s tap should be at least 0.2 mg/Lor at a level specified by the state. This level helps ensure that the water is free from harm-ful bacteria. However, higher levels may be necessary to control special problems, such as
FIGURE 6-1 Formation of combined chlorine residual and free available chlorine residual
1 2 3 4C
hlor
ine
Res
idua
l
Chlorine Added
CombinedResidual
FreeAvailableResidual
Breakpoint Chlorination Curve
Chl
orin
e D
estr
oyed
by R
educ
ing
Com
poun
ds Formation of ChlorooranicsandChloramines
Free AvailableResidual Formed(Some Chloroorganicsand ChloraminesRemain)
Chl
oroo
rgan
ics
and
Chl
oram
ines
Par
tly D
estr
oyed
Bre
akpo
int
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iron bacteria. If maintaining a free chlorine residual in a distribution system becomes dif-ficult, several possible problems are indicated. Stagnant water in dead ends or storagetanks, biological growths, contamination of mains during main-break repair, and contam-ination caused by cross-connections all cause dissipation of free chlorine residuals. Fur-ther, a drop in chlorine residual in the distribution system may indicate inadequacies in thetreatment process itself.
Chlorine DemandTest results for chlorine residual can be combined with operating data regarding theamount of chlorine added at the plant to yield information on chlorine demand. Chlorinedemand is a measurement of how much chlorine must be added to the water to achievebreakpoint chlorination or whatever free chlorine residual is desired.
The most significant reason for analyzing a water supply’s chlorine demand is todetermine the proper dosage. However, changes in chlorine demand can also indicatewater quality changes. For example, if a water supply suddenly requires more chlorine tomaintain a residual (that is, if the water exhibits a higher chlorine demand), then the chlo-rine is oxidizing some contaminants that previously were not present in the water supply.
When chlorine demand increases, two steps are necessary. First, the chlorine dosemust be increased to meet the higher demand. Second, the reason for the increaseddemand should be investigated. A sudden increase in chlorine demand frequently occursin surface water because of seasonal water quality changes. Chlorine demand in ground-water should not change substantially because the quality of groundwater is usually verystable.
DISINFECTION BY-PRODUCTSThe disinfection by-products (DBPs) currently regulated are the trihalomethanes and thesum of five haloacetic acids (HAA5). Continuing studies and research have revealed thatchlorine (and all other alternate disinfectants) reacts with organic compound precursorsin the water to form many different kinds of organic compounds. In current thinking,many of these compounds are considered to be potentially toxic and are suspected ofbeing carcinogenic. Haloacetic acids, halonitriles, haloaldehydes, and chlorophenols arejust a few of the organic compounds associated with chlorine disinfection. Thus, chlorina-tion has its good and its bad points; the water plant operator must know how to ade-quately disinfect the water without producing undesirable levels of DBPs.
SamplingChlorine residual sampling is done at the treatment plant and at the consumer’s faucet.
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INORGANIC CHEMICALS 149
Treatment plant samplingIn-plant sampling of chlorine residual determines whether sufficient chlorine has beenadded to the water before it leaves the treatment plant. This is the only way to be sure thatfinished water leaving the plant contains the desired chlorine residual. Obtaining represen-tative samples is the most critical part of in-plant chlorine sampling.
In some instances, a sample must be collected at a point near the location of chlorineaddition. In this case, analyses will probably show disproportionately high chlorine resid-ual. To obtain data that approximate the actual chlorine residual in a particular basin, thesample should be held for a time period equal to the basin detention time or, in any case,at least 10 minutes. Under requirements of the Surface Water Treatment Rule, surfacewater systems serving populations larger than 3,300 are required to provide continuouschlorine residual monitoring where the water enters the distribution system.
Distribution system samplingFor systems that chlorinate, sampling for chlorine residual from the distribution system isdone to determine whether consumers are receiving water that is of good quality. In otherwords, if there is no chlorine residual, the operator will have to determine the cause of thereduced residual and take corrective measures to restore the chlorine residual to the areato ensure the safety of the water supply. If the water samples are positive for bacteria andchlorine residual is analyzed at the time of sample collection the information regardingthe level of chlorine residual may aid in determining if the contamination was in the watersample or if the equipment used for the analysis was contaminated. A strong chlorineresidual in the sample collected may indicate that the water was not contaminated.
If analysis is made in the field, only about 10 mL of sample are required. Current regu-lations require that chlorine residual samples taken for compliance samples must be ana-lyzed immediately or at the most within 15 minutes of collection. If samples must be taken toa laboratory, a 100-mL sample should be collected. Analysis should be completed as soon aspossible after collection. There is no recommended preservation for chlorine samples; chlo-rine is unstable in water and residual chlorine will continue to diminish with time, and soimmediate field testing is preferred. Chlorine analyses performed after the 15 minute win-dow are not considered acceptable results for compliance testing for regulatory purposes.
Agitation or aeration of the sample should be avoided because it can cause reductionof the sample’s chlorine concentration. Chlorine will also be destroyed and subsequentanalysis will be erroneously low if samples are exposed to sunlight. The same sample bottleshould never be used for both chlorine residual and coliform analyses. Bottles used for coli-form analysis contain a chemical (sodium thiosulfate) that neutralizes the chlorine residual.
Methods of DeterminationThe N,N-diethyl-p-phenylenediamine (DPD) test kit is the simplest and quickest way totest for residual chlorine. The test takes approximately 5 minutes to complete. The oldorthotolidine method has been eliminated as an acceptable method and should not be
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used. It is not as accurate as the DPD method, particularly for measuring free chlorineresidual.
Another technique, used primarily in laboratories because of its accuracy, is ampero-metric titration. The method is unaffected by sample color or turbidity, which can inter-fere with colorimetric determinations. However, performance of amperometric titrationrequires greater skill and care than does the DPD method. Because of the equipment andsample volumes required, the amperometric method is normally not used as a field testoutside of the treatment plant.
The chlorine demand can be determined by treating a series of water samples withknown but varying chlorine dosages. After an appropriate contact time, the chlorine resid-ual of each sample is determined. This procedure indicates which dosage satisfied thedemand and provided the desired residual.
DISSOLVED OXYGENDissolved oxygen (DO) in water is not considered a contaminant. Either an excess or alack of DO does, however, help create unfavorable conditions. Generally, a lack of DO innatural waters creates the most problems, specifically an increase in tastes and odors as aresult of anaerobic decomposition.
The amount of DO in water is a function of the water’s temperature and salinity. Coldwater contains more DO, and saline water contains less DO. Natural waters are seldom inequilibrium (exactly saturated with DO). Temperature changes as well as chemical andbiological activities all use or release oxygen, causing the amount of DO in water tochange continually.
SignificanceNominal levels of DO in municipal water supplies are generally not a problem. Dissolvedoxygen has no adverse health effects and actually increases water’s palatability. Most con-sumers prefer water that has a DO content near the saturation point. However, a concen-tration this high is detrimental to metal pipes because oxygen helps accelerate corrosion.
Introducing oxygen into water can be a method of treatment for purposes such as oxi-dizing iron and manganese into forms that will precipitate out of the water. Dissolved oxy-gen also has the ability to remove excess carbon dioxide. It degrades some organiccompounds that cause taste and odor problems, provided the contact time is long enough.
Where additional DO is desired for water treatment, some form of aeration is used. Var-ious types of aeration processes are detailed in Water Treatment, another book in this series.
DO data from raw-water storage-reservoir samples can also be used to indicate thegeneral quality of the water. On the basis of these data, operators may be able to maketreatment changes or alter the way the reservoir releases are made to prevent taste, odor,and other problems.
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INORGANIC CHEMICALS 151
SamplingDO analyses should be conducted routinely on raw-water samples from surface watersources, particularly if storage reservoirs are being used. Treated-water samples shouldalso be analyzed routinely if aeration is used as a treatment process; otherwise the testsmay be conducted on a weekly basis for general quality data.
DO should be determined on-site if the electrode method (see next section) is used. If themodified Winkler test (see next section) is being used, the sample must be collected in a glassbottle and “fixed” (treated with a chemical additive to retard change) on site. The sampleshould be stored in the dark at the temperature of the collection water or water sealed andkept at a temperature of 50°F to 68°F (10°C to 20°C) until the analysis can be performed.
Methods of DeterminationThe electrode method and the modified Winkler method (also called the iodometricmethod) are preferred for DO measurements. Because the electrode method is not as sensi-tive to interferences as is the modified Winkler test, it is excellent for analyzing DO in pol-luted waters, highly colored waters, and strong waste effluents. Drinking waters and supplyreservoirs have few interferences that cause problems with the modified Winkler procedure.
INORGANIC METALSThe effects of metal in water are varied. Table 1-1 in chapter 1 provides information oninorganic contaminants including metals covered under the National Primary DrinkingWater Regulations, the MCLG, MCL, or treatment technique. Information is providedabout potential health effects from ingestion of water, sources, and treatment technologyinformation.
Three types of metals are discussed in this section. Dissolved metals are metals in anunacidified sample that pass through a 0.45-μm membrane. Suspended metals are metalsin an unacidified sample retained by a 0.45-μm membrane. Total metals are the sum ofsuspended and dissolved metals or the concentration determined in an unfiltered digestedsample.
Sampling and Sample PreservationBefore collecting a sample, it must be decided what fraction is to be analyzed (dissolved,suspended, total, or acid extractable). This decision will determine in part whether thesample is acidified with or without filtration and the type of digestion required.
Serious errors may be introduced during sampling and storage because of contamina-tion from the sampling device, failure to remove residues of previous samples from thesample container, and loss of metals by adsorption on or precipitation in the sample con-tainer caused by failure to acidify the sample properly.
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Sample containersBecause of expense, the preferred sample container is made of polypropylene or linearpolyethylene with a polyethylene cap. Borosilicate glass containers also may be used, butsoft glass containers should be avoided for samples containing metals in the microgram-per-liter range. Samples should be stored for determination of silver in light-absorbingcontainers. Only containers and filters that have been acid rinsed should be used.
PreservationThe samples should be preserved immediately after sampling by acidifying with concen-trated nitric acid (HNO3) to pH <2. The samples should be filtered for dissolved metalsbefore preserving. Usually 1.5 mL concentrated HNO3 added to a liter sample (or 3 mL1 + 1 HNO3 added to a liter sample) is sufficient for short-term preservation. For sam-ples with high buffer capacity, the amount of acid should be increased (5 mL may berequired for some alkaline or highly buffered samples). The sample should be checkedto ensure the pH of the sample has been reduced to below 2. Commercially availablehigh-purity acid should be used.
After acidifying the sample, it is preferable to store it in a refrigerator at approximately4°C. Under these conditions, samples with metal concentrations of several milligrams perliter are stable for up to six months (except mercury, which is stable up to five weeks).
Methods of DeterminationThe presence of metals is determined using both colorimetric and instrumental methods.Instrumental methods include atomic absorption spectrometry, which includes flame, elec-trothermal (furnace), hydride, and cold-vapor techniques; flame photometry; inductivelycoupled plasma emission spectrometry; inductively coupled plasma mass spectrometry;and anodic stripping voltametry.
Sources of ContaminationIntroducing contaminating metals from containers, distilled water, or membrane filtersshould be avoided. Some plastic caps or cap liners may introduce metal contamination;for example, zinc has been found in black Bakelite-type screw caps as well as in many rub-ber and plastic products, and cadmium has been found in plastic pipette tips. Lead may bea contaminant in urban air and dust depending on the industry, construction, and demo-lition taking place in areas where lead may have been used in the past. It used to be foundin gasoline, so the by-products of gasoline engine use would have contained lead, whichmay have been deposited on a variety of surfaces including the soil in the area.
Take care not to introduce metals into samples during preliminary treatment. Duringpretreatment, contact with rubber, metal-based paints, cigarette smoke, paper tissues, and allmetal products including those made of stainless steel, galvanized metal, and brass shouldbe avoided. Conventional fume hoods can contribute to sample contamination, particularly
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during acid digestion in open containers if the solutions boil and splatter their contents toadjoining sample containers. Vessels should be covered with watch glasses and spoutsturned away from incoming air to reduce airborne contamination. Plastic pipette tips oftenare contaminated with copper, iron, zinc, and cadmium. Colored plastics, which can containmetals, should not be used. Certified metal-free plastic containers and pipette tips should beused when possible. Glass should not be used if analyzing for aluminum or silica.
Metal-free water should be used for all operations. Reagent-grade acids used for pres-ervation, extraction, and digestion should be pure. If excessive metal concentrations arefound, ultrapure acids should be used. Blanks should be processed through all digestionand filtration steps, and blank results should be evaluated relative to corresponding sam-ple results. Either corrections should be applied to sample results or other correctiveactions should be taken as necessary or appropriate.
Inorganic Nonmetallic CompoundsInorganic nonmetallic contaminants include cyanide, fluoride, nitrate, and nitrite. Theanalytical methods used for determination include wet-chemical techniques and instru-mental methods such as ion chromatography.
Nitrate can occur in trace quantities and in high concentrations in surface water andgroundwaters depending on the type of soil and the land uses in the watershed for surfacewater or the recharge zones for wells. Nitrite is an intermediate product formed whenammonia is oxidized to nitrate and when nitrate is reduced. Cyanide is not normallyfound in either surface water or groundwater. Fluoride, iron, and manganese are discussedin detail in the following sections.
FLUORIDEFluoride is found naturally in many waters. It is also added to many water systems toreduce tooth decay.
SignificanceResearch has demonstrated that drinking water containing a proper amount of fluorideresults in reduction in tooth decay during the years of children’s tooth formation (frombirth to between the ages of 12 and 15). This is assuming that the children are actuallydrinking the tap water in the appropriate amounts to provide them with the correct dosefor their age and body mass.
Fluoride concentrations in drinking water that are optimum for reducing tooth decayare based on average air temperature. Depending on air temperature, the regulatory agenciesset the levels the treatment plants that feed fluoride are allowed to introduce. Because morewater is consumed in warmer climates, fluoride concentrations should be lower in theseareas. Excessive fluoride concentrations can cause teeth to become stained or mottled.
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This problem generally occurs only where natural fluoride concentrations exceed 2.0 mg/L(the secondary MCL).
Close control of fluoride concentrations is necessary to ensure the maximum benefitof fluoridation with an adequate margin of safety. A reduction of only 0.3 mg/L below theoptimum concentration can drastically reduce the dental benefits of fluoride. Specificguidelines from the state should be obtained concerning recommended concentrations fora given water supply if fluoride is being added to the water.
SamplingFluoride samples should be collected from raw and finished water in polyethylene bottles.Raw-water samples are necessary because the total amount of fluoride reaching the con-sumer is equal to the fluoride concentration in the raw water plus the fluoride added at theplant. Although the fluoride level in most source water is fairly stable, it can vary some-what and so should be periodically analyzed. The amount of fluoride to be added to theraw water is calculated by subtracting the raw-water concentration from the desiredtreated-water concentration.
Finished-water samples are tested to ensure that the fluoride feeders are operatingcorrectly and the final fluoride concentration is at the desired level. Nearly all regulatoryagencies require that samples of the plant effluent be tested daily.
Samples collected for fluoride analysis may be held for 7 days before analysis. Theyshould be stored in a refrigerator at 39°F (4°C) with no preservatives added.
Methods of DeterminationTwo methods for fluoride analysis are commonly used: the SPADNS (sodium,2-(parasulfo-phenylazo)-1.8-dihydroxy-3,6-naphthalene disulfonate) method and the electrode method.The electrode method requires a selective ion fluoride electrode connected to a pH meterwith a millivolt scale or to a meter having a direct concentration scale for fluoride. Witheither method, interferences may require a distillation step prior to the test. The water to betested should be checked for interferences that might be present.
IRONIron occurs naturally in rocks and soils and is one of the most abundant of all elements. Itexists in two forms: ferrous (Fe+2) and ferric (Fe+3). Ferrous iron is found in well watersand in waters with a low level of dissolved oxygen. Under anaerobic conditions, waterscan have significant dissolved-iron concentrations.
Dissolved iron in water is derived naturally from soils and rocks. It may also resultfrom the corrosive action of water on unprotected iron or steel mains, steel well casings,and tanks. Surface waters may also occasionally contain appreciable amounts of iron thatoriginates from industrial wastes or from acid runoff from mining operations.
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SignificanceIron at levels normally found in properly treated drinking water does not present a healthissue. Even though iron poisoning can take place the normal dosage would be in the rangeof 20 mg/kg or above for symptoms of iron toxicity to develop. Water quality limits onallowable concentrations of iron in water supplies are based on the problem of discolorationand undesirable taste and of the iron staining porcelain plumbing fixtures. Iron concentra-tions above 0.3 mg/L can cause undesirable “red water.” Concentrations at or above thislevel in finished water indicate that steps should be taken to remove iron. Details on ironremoval and control methods are detailed in Water Treatment, another book in this series.
Iron also provides a nutrient source for some bacteria that grow in distribution sys-tems and wells. Iron bacteria, such as Gallionella, cause red water, tastes and odors,clogged pipes, and pump failure.
Whenever tests show increased iron concentrations between the water plant and theconsumer’s tap, corrosion and/or iron bacteria may be present, and corrective actionshould be taken. If the water is corrosive, pH adjustment might be considered first. If theproblem is caused by bacteria, flushing of the mains, shock chlorination (temporarily highconcentrations), or increased everyday chlorination may prove effective.
SamplingSamples should be taken from raw and finished water. The samples should be collected inglass or plastic bottles and may be stored as long as 6 months before analysis. At least100 mL of sample should be collected. Samples should be preserved with approximately0.5 mL of concentrated nitric acid per 100-mL sample to lower the pH to less than 2.
Methods of DeterminationIron concentration may be determined by the phenanthroline method or the atomicabsorption spectrophotometric (AA) method. The phenanthroline method is simple andreliable. It is a colorimetric test and can be run with a spectrophotometer or filter photo-meter. The AA method, used by large laboratories, is very accurate and is particularlyadvantageous when large numbers of samples must be tested. Another method allowed inthe regulations is Inductively Coupled Plasma (ICP) analysis.
MANGANESEManganese, a metal, creates problems in a water supply similar to those created by iron.Manganese occurs naturally in ores but not in a pure state. It exists in soils primarily asmanganese dioxide. It is found both in the manganous divalent form (Mn+2) and in thequadrivalent form (Mn+4). Manganese is much less abundant in nature than is iron; there-fore, it is found less often in water supplies and is often present at lower concentrations.
156 WATER QUALITY
It is also more difficult than iron is to oxidize or cause to precipitate because manganoussolutions are more stable than are ferrous solutions.
The most common forms of manganese—oxides, carbonates, and hydroxides—areonly slightly soluble. Consequently, manganese concentrations in surface waters seldomexceed 1.0 mg/L. In groundwaters subject to anaerobic or reducing conditions, manganeseconcentrations, like iron concentrations, can become very high.
SignificanceConsumption of manganese when it is present in properly treated drinking water has shownno known harmful effects on humans. Water quality limits on allowable concentrations ofmanganese have been based on aesthetic problems rather than health concerns. Manganesedoes not usually discolor water, but it stains clothes and bathroom fixtures black. Stainingproblems can begin at 0.05 mg/L, a much lower concentration than for iron.
Raw-water and finished-water analyses will indicate whether manganese removal isnecessary or whether the desired removal has been achieved in the treatment plant.Increases in manganese concentration in the distribution system are not generally experi-enced, except that a rapid flow change in the distribution system may result in somedeposits breaking loose and entering consumers’ water. This problem is best controlled byflushing the lines in areas where the problem occurs.
SamplingSamples for manganese analysis should be taken from raw and finished water. The sam-ples should be collected in glass or plastic bottles and may be stored as long as 6 monthsbefore analysis. At least 100 mL of sample should be collected. Samples should be pre-served with concentrated nitric acid. Approximately 0.5 mL of concentrated nitric acid per100-mL sample should be added to lower the pH to less than 2.
Methods of DeterminationThe AA method or ICP mass spectroscopy (ICPMS) analysis are the preferred methodsof determination. Also approved for use are colorimetric methods, which are more readilyavailable and economical for the treatment plant operator.
pHpH is a measure of the hydrogen ion concentration present in water, or it can be stated asthe logarithm of the reciprocal of the hydrogen ion concentration, which is the same as thenegative log10 of the hydrogen ion concentration in water.
pH = log10 1/[H+]= –log10 [H+]
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Expression of pHBecause pH is a logarithmic function, small changes in the measured pH mean largechanges in the hydrogen ion concentration. The usual method for reporting pH results isto present the high and low pH along with an average pH or median value depending onwhat the reporting agency requests.
Importance of pHpH controls many chemical reactions, including coagulation, disinfection, water soften-ing, corrosion, biochemical reactions, and ammonia removal. It can be affected by manyof the treatment processes in the plant, including ion exchange, corrosion control, disin-fectant chemicals, aeration, and coagulation, to name a few. It also indicates to the designengineer what construction materials to use. A question often asked in water treatment is“How many pH meters should I install and where do I put them?”
SELECTED SUPPLEMENTARY READINGSClement, B. 1992. Computers Can Reduce Langelier Index Test Time. Opflow, 18(3):1.
Gordon, G., W.J. Cooper, R.G. Rice, and G.E. Pacey. 1992. Disinfectant ResidualMeasurement Methods. 2nd ed. Denver, CO: American Water Works Association andAmerican Water Works Association Research Foundation.
Manual M12, Simplified Procedures for Water Examination. 2001. Denver, CO:American Water Works Association.
Manual of Instruction for Water Treatment Plant Operators. 1991. Albany, N.Y.: NewYork State Department of Health.
Manual of Water Utility Operations. 8th ed. 1988. Austin, Texas: Texas Water UtilitiesAssociation.
Methods of Chemical Analyses of Water and Wastes. 1984. EPA-600/4-79-020. Cincinnati,Ohio: US Environmental Protection Agency.
Standard Methods for the Examination of Water and Wastewater. 21st ed. 2005. A.D.Eaton, L.S. Clesceri, and A.E. Greenberg, eds. American Public Health Association,American Water Works Association, and Water Environment Federation.
Stubbart, J., W.C. Lauer, and T.J. McCandless. 2004. AWWA Water Operator FieldGuide. Denver, CO: American Water Works Association.
Water Quality and Treatment. 6th ed. 2010. New York: McGraw-Hill and AmericanWater Works Association (available from AWWA).
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159
C H A P T E R 7
Organic Contaminants
All organic compounds or contaminants contain carbon in combination with one or moreelements. Organic compounds comprising the group called hydrocarbons contain only car-bon and hydrogen (Figures 7-1 and 7-2). Many organics contain carbon, hydrogen, andoxygen. Naturally occurring organic compounds often contain low concentrations ofnitrogen, phosphorus, and sulfur. Synthetic organic compounds may contain halogens—for example, chlorine or fluorine, and inorganic metals.
NATURAL ORGANIC SUBSTANCESOrganic compounds differ from inorganic metallic and nonmetallic compounds. In gen-eral, the following characteristics describe organic compounds, but these may not beapplicable in all cases.
• are combustible,• have lower melting and boiling points,• are only slightly soluble in water,• exhibit isomerism, in which more than one compound may exist for a chemical
formula,• have very high molecular weights,• serve as substrate or food for bacteria, and• have slower reaction rates.
Organic compounds find their way into water from three sources. The first source ishumic materials from plants and algae, microorganisms and their secretions, and hydro-carbons. A few of the aromatic hydrocarbons may cause adverse health effects. Humicmaterials are precursors in the formation of trihalomethanes (THMs).
The second source is domestic and commercial activities and effluent from waste-water treatment plants and industries into surface waters such as rivers.
The third source is reactions that occur during water treatment and transmission.
GroundwaterIt is usually rare for groundwater sources to contain elevated levels of natural organic com-pounds, but one situation in which such levels can occur is in a relatively shallow well over-lain by an existing or previously swampy area. If the taste, odor, and/or color are excessive,treatment may have to be provided to make the water palatable in the same manner as for asurface water source. It is not likely that such naturally occurring contaminants alone will
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create a serious health hazard. In such cases, if the amount of organic matter in the ground-water is relatively modest, it may not adversely affect taste, odor, or color. However, it mightcreate excessive levels of disinfection by-products (DBPs) when the water is chlorinated.
Groundwater is also occasionally contaminated by naturally occurring hydrocarbons.In areas where natural gas and oil come in contact with aquifers, the water may be slightlycontaminated but still usable, with treatment, as a drinking water source. If the water isheavily contaminated, it will probably not be a suitable water source.
Recent studies have shown that groundwater can be contaminated with syntheticorganic compounds (SOCs) created for use by industries (electronics, metals), military uses
FIGURE 7-1 Typical arrangement of carbon atoms
FIGURE 7-2 Typical hydrocarbons in chain configuration
C
C
C C
C C
C
C
C
C
C C
C
C
C
C
Consecutive Chain Branched Chain
C C
C C
C
C
C
C
CRing With One Branch Ring With One Branch
(alternate representation)Three-Dimensional
Framework
H H
H
H
C H H
H
H
C
H
H
C
H H
H
H
C
H
H
C
H
H
C H HC
H
H
C
H
H
C
H
H
C
H
H
Methane — CH4 Ethane — C2H6
Butane — C4H10Propane — C3H8
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ORGANIC CONTAMINANTS 161
(explosives, rocket fuels) and in the production and use of fossil fuels, such as oxygen enhanc-ing compounds. Some of these compounds have been found to attach themselves to watermolecules and move through the soil layers to become part of the groundwater makeup.
Surface WaterIn general, surface waters are more prone to contamination by natural organic com-pounds than are groundwaters. The various types of vegetation growing in the watershedare one source of contamination. Many water systems regularly experience operationalproblems caused by decaying leaves and plants that have been washed from farms and for-ests during heavy rains in the spring and fall. This organic matter is generally decomposedby biological action and breaks down eventually into carbon dioxide and water. However,some organic compounds are quite complex and persist in the water environment forsome time. For example, humic acid, derived from the decomposition of plant matter, isfound in most surface waters and does not readily biodegrade (break down).
Microorganisms are another source of organic compounds in water. In addition tocellular matter, many plants and microorganisms release organic matter into a watersource through their metabolic processes.
Various types of algae and vegetation flourishing in a lake or reservoir can also be thesource of objectionable organic compounds in water. If the concentration of this vegeta-tion is low, it usually has no adverse effect on drinking water quality. However, a suddendie-off of the vegetation can cause deterioration in water quality. Some adverse healtheffects of large quantities of certain blue-green and red algae may also occur.
Serious taste and odor problems can also be caused when a reservoir becomes strati-fied and matter near the bottom that has decomposed anaerobically (in the absence of freeoxygen) is brought into the water system. Excessive amounts of algae in source water canalso cause water treatment problems such as taste and odor, filter clogging, and formationof slime in the treatment plant.
DBPs form when water containing organic substances is disinfected. In most cases,the organic substances are naturally occurring, such as humic and fulvic acids resultingfrom decaying vegetation. A group of chlorinated organic compounds called THMs wasone of the first products of the reaction of chlorine with humic substances to be recog-nized. The principal THMs of concern are chloroform, bromodichloromethane, chlorodi-bromomethane, and bromoform. At one time, chloroform was widely used in coughmedicine and other medications, but its use was discontinued when research determinedthat chloroform was thought to be carcinogenic. The other THMs are also suspected ofbeing carcinogens or have been demonstrated to have other adverse health effects such aspossible birth defects. These issues are being studied to determine if any of this is fact.Thus, the various THMs are regulated as a group, with a maximum contaminant level(MCL) established for total THMs.
As more knowledge about DBPs develops, additional regulations limiting their con-centration in finished water are expected. The next DBPs being considered for regulation
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are a group of five haloacetic acids, abbreviated as HAA5. DBPs are discussed in moredetail in chapter 1.
Domestic and commercial activities contribute synthetic organic chemicals (SOCs) towastewater discharges, agricultural runoff, urban runoff, and leachate from contaminatedsoils. Most of the organic contaminants identified in water supplies as having adversehealth concerns are part of this group. They include pesticides (such as atrazine and aldi-carb), solvents and metal degreasers (such as trichlorobenzene, tetrachloroethylene,trichloroethylene, and trichloroethane), and a family of compounds formerly in wide use,the polychlorinated biphenyls.
Organic contaminants formed during water disinfection include by-products such asTHMs (e.g., chloroform) and HAAs (e.g., di- and trichloroacetic acids). Other compounds,such as acrylamide or epichlorohydrin, are components of coagulants (e.g., polyacrylamide)that can leach out during treatment. During finished-water transmission, undesirable com-ponents of pipes, coatings, linings, and joint adhesives, such as polynuclear aromatic hydro-carbons (PAHs), epichlorohydrin, and solvents, have been shown to leach into water. Thissmall amount of leaching decreases as the pipe ages.
SYNTHETIC ORGANIC SUBSTANCESThe category of synthetic organic chemicals (SOCs) has become a regulatory rather than achemical description. It has evolved to distinguish a group of mostly volatile organicchemicals (VOCs), regulated first under the 1986 amendments of the federal Safe Drink-ing Water Act, from “SOCs” regulated under Phase 2 and later regulations. However,some of those SOCs are also VOCs (e.g., ethylbenzene, styrene, toluene, and xylenes, andthe fumigant pesticides). The bulk of SOCs are pesticides but also include the PAHs, thepolychlorinated biphenyls, and two water treatment polymers.
HEALTH EFFECTS OF ORGANIC CHEMICALSThe USEPA has designated three health-effects categories for organic chemicals:
• Category I—It is known, or there is strong evidence, that the chemical is a carcinogen.• Category II—There is limited but not positive evidence that the chemical is a carcino-
gen, and there are other known adverse health effects.• Category III—There is no firm evidence that the chemical is a carcinogen, but there
are other known adverse health effects.
NoncarcinogensTo the water system operator, the principal significance of a chemical’s carcinogenic status isthe way the maximum contaminant level goal (MCLG) is established. For noncarcinogens,the MCLG is a number indicating the level of the contaminant that health-effects experts
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consider acceptable in drinking water. The MCL is then set at the same level as the MCLG,or as close to it as is considered technically achievable. The MCLG for these contaminantswill be changed only if new information on their toxicity to humans becomes available.
The noncarcinogenic effects of organic chemicals on humans vary; damage to theliver, kidneys, cardiovascular system, and central nervous system are the principal effects.
CarcinogensFor carcinogens, USEPA policy is that the MCLG must be zero. In other words, it is pres-ently assumed that any exposure to the chemical could cause cancer, so ideally none of thechemical would be present in drinking water.
In the real world, though, there are two restrictions in controlling carcinogens: (1) theability to detect the chemical by reasonable and reliable laboratory technique and (2) thetechnology to remove the chemical from water if it is found to be present. These factorsare considered when the MCLs are established, and the MCLs are set as close to theMCLGs as experts consider to be realistically achievable.
From time to time, then, USEPA must review all MCLs for carcinogens, and if thefactors considered in setting the MCL have changed, the MCL will be changed. In short,the intention is to continually edge the MCL for carcinogens closer to zero, so the allow-able level is likely to be changed periodically. This may occur as the methods of testingimprove or as further data are reviewed and proven to be of merit. So far the only contam-inants that have had a change in status are nickel (delisted) and arsenic (MCL reducedfrom a level of 50 μg/L to 10 μg/L).
MEASUREMENT OF ORGANIC COMPOUNDSNo single analytical method is capable of measuring all of the organic substances in awater sample. However, available analytical methods can be grouped into two categories,general and specific.
General Analytical MethodsThreshold odor tests, flavor profiles, and color determinations, described in chapter 5,have been used in the water utility industry for many years to obtain general measures ofthe levels of natural organic compounds in water. Two other methods used occasionally inmonitoring water quality are ultraviolet light absorbance and fluorescence. These tests areused in some plants for control of organic compound removal processes because the mea-surement can be made quickly and easily.
Another test commonly used to determine the overall content of organic compoundsin water is the measurement of total organic carbon (TOC). The typical concentration ofTOC in water sources ranges from less than 0.5 mg/L to more than 10 mg/L. Highly col-ored water may have a TOC concentration of more than 30 mg/L.
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Total organic halogen (TOX) is another measurement that is being used increasinglybecause it is specific to halogenated organic compounds. The presence of TOX in a sampleis an indication of the presence of either synthetic organic compounds or DBPs. Onlyfairly sophisticated laboratories are currently capable of carrying out the procedures forTOC and TOX determinations.
Specific Analytical MethodsThe list of organic compounds that have been identified in drinking water samples hasgrown from approximately 200 in 1975 to thousands today, and it is constantly lengthen-ing. In many cases, of course, a compound may have been identified only in isolated sam-ples or at extremely low concentrations. However, the growth in the list is primarilybecause of steadily increasing improvements in analytical methods.
The three fundamental steps in the analysis of organic compounds are
1. extraction and concentration of the organic compounds in the sample,2. separation of the extracted organic compounds in a gas chromatograph, and3. detection of individual compounds.
Gas chromatography (Figure 7-3) requires very specialized equipment, detailed pro-cedures, and trained operators, but in general the three steps are as follows.
Extraction and concentrationOrganic substances are first extracted from a water sample. One method uses an organicsolvent such as methylene chloride or pentane. This process is called liquid–liquid extrac-tion. Another method strips the organic compounds out of the sample using an inert gassuch as nitrogen or helium. This process is called purge-and-trap analysis.
SeparationThe complex solution must then be separated into its individual organic components. Thisprocess is carried out with a gas chromatograph or a high-performance liquid chromato-graph. Chromatographs have a column of long, thin tubing through which individualorganic compounds are driven off the sample as the temperature is elevated. Thus, theseprocesses may be viewed as sophisticated distillation or separation functions.
DetectionAs the chromatograph separates the organic compounds by the temperature at which theyare vaporized, they travel to a detector. Several types of detectors are available, each withcertain advantages and disadvantages. The types in general use include flame ionization,electron capture, electrolytic conductivity, photoionization, and mass spectrometry. Anorganic compound is identified by comparing the signal the detector obtains (shown
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ORGANIC CONTAMINANTS 165
graphically in a gas chromatograph [GC] generated by the detector) with known stan-dards for the compound. This process is generally aided by a computer connected to theequipment.
Figure 7-4 shows a chart produced by a GC, showing the presence of trihalomethanesin a water sample.
Sampling for Organic CompoundsThe location of sampling points in a water distribution system is very important; certain pointsshould definitely not be used. The following are among typical locations to be avoided:
• Public restrooms should not be used as sampling locations because the deodorizercommonly used in restrooms contains an organic chemical that may be in the air insufficient concentration to contaminate the water sample.
• Gasoline service stations should be avoided because of the prevalence of petroleumproducts that could be in the air or that could have gotten on the sampling faucet.
• Any location where there are unusual odors, such as a freshly painted room, or wherethere is a smell from cleaning materials, should be avoided.
FIGURE 7-3 Steps in gas chromatography
Oven
Chromatographic Column
CarrierGas
Gas Chromatograph
Liquid–Liquid Extractionor
Gas Purge
1. Extraction and Concentration
2. Separation
3. Detection
Time
Res
pons
e
Gas ChromatogramDetector
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166 WATER QUALITY
• A location where a pump or piping has recently been installed or repaired, especiallyif organic solvents have been used for cleaning and degreasing, should be avoidedbecause of the possibility that organic solvents may have been used in the plumbing.
• Other unsuitable locations are those where solvents may be present in the atmospheresuch as paint or hardware stores, barber and beauty shops (hair spray, etc.) and dry-cleaning establishments.
Ultraclean glass vials having lids with polytetrafluoroethylene (PTFE; trade nameTeflon®) liners are used for collecting volatile organic compound samples. The samplesmust be collected so that there is zero headspace in the vial; in other words, there must beno bubble of air in the vial after it is filled. If any air remains in the vial, a portion of themore volatile organic compounds will come out of solution and into the air space, whichwill cause inaccurate analysis of the water sample. Trip blanks and field blanks should alsobe incorporated into the normal sampling practices.
Each sample container must be completely labeled. A general rule is that the descrip-tion of the sampling site must be complete enough so that a person unfamiliar with the ini-tial sampling could return and collect a repeat sample from the same location if necessary.
FIGURE 7-4 Sample readout from a gas chromatograph
1
2
3
4
Det
ecto
r R
espo
nse
Retention Time, minutes
0.00 3.35 4.00 5.20 7.50
Key1. Chloroform,100 μg/L2. Dichlorobromomethane, 5 μg/L3. Dibromochloromethane, 4 μg/L4. Bromoform, 2 μg/L
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ORGANIC CONTAMINANTS 167
SELECTED SUPPLEMENTARY READINGSAWWA Organic Contaminants Control Committee. 2008. Emerging Organic Contaminants:
What Are They? Opflow, 34(1):16–17.
AWWA Organic Contaminants Control Committee. 2008. Treating Water Nature’sWay. Opflow, 34(4):14–16.
Manual of Water Utility Operations. 8th ed. 1988. Austin, Texas: Texas Water UtilitiesAssociation.
Standard Methods for the Examination of Water and Wastewater. 21st ed. 2005. A.D.Eaton, L.S. Clesceri, and A.E. Greenberg, eds. Washington, D.C.: American PublicHealth Association, American Water Works Association, and Water EnvironmentFederation.
Water Quality and Treatment. 6th ed. 2010. New York: McGraw-Hill and AmericanWater Works Association (available from AWWA).
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C H A P T E R 8
Radiological Contaminants
One of the more significant public health concerns regarding drinking water is the rela-tively high level of natural radioactivity found in some water sources. Most radioactivityin water occurs naturally, but there is also a threat of radionuclide contamination fromvarious industrial and medical processes.
The harmful effects to a living organism of consuming water containing radioactivityare caused by the energy absorbed by the cells and tissues of the organism. This absorbedenergy (or dose) produces chemical decomposition of the molecules present in the livingcells. Each of the forms of radiation reacts somewhat differently within the human body.
RADIOACTIVE MATERIALSA radioactive atom (Figure 8-1) emits alpha particles, beta particles, and gamma rays.
Alpha Particles (Radiation)Alpha particles are the most prevalent naturally occurring radionuclide present in drinkingwater and are therefore of the greatest concern. Alpha (a) particles are the heaviest particles.
FIGURE 8-1 Emissions from the nucleus of a radioactive atom
BetaParticle
AlphaParticle
Gamma Ray
Nucleus of a Radioactive Atom
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Alpha radiation is not true electromagnetic radiation like light and X-rays. It consistsof particles of matter. Alpha particles are doubly charged ions of helium. Although theyare propelled from the nucleus of atoms at approximately 10 percent of the speed of light,they do not travel much more than 10 cm in air at room temperature. They are stopped byan ordinary sheet of paper. The alpha particles emitted by a particular element are allreleased at the same velocity. The velocity varies, however, from element to element. Alphaparticles have extremely high ionizing action within their range.
Beta RadiationBeta radiation consists of negatively charged particles—electrons—that move at speedsranging from 30 to 99 percent of the speed of light. The penetrating power of beta radia-tion depends on its speed. It can travel several hundred feet in air and can be stopped byaluminum a few millimeters thick. The ionizing power of beta radiation is much less thanthat of alpha radiation.
Gamma RadiationGamma radiation is true electromagnetic radiation, which travels at the speed of light. Itis similar to X-ray radiation but has a shorter wavelength and therefore greater penetrat-ing power, which increases as the wavelength decreases. Proper shielding from gammaradiation requires a barrier of lead that is several centimeters thick or concrete several feetthick. The unit of gamma radiation is the photon.
Unit of RadioactivityThe measurement of radioactivity disintegration is expressed in curies. Formerly, one unitof radioactivity was considered to be the number of disintegrations occurring per secondin one gram of pure radium. Because the constants for radium are subject to revision fromtime to time, the International Radium Standard Commission has recommended the useof a fixed value, 3.7 × 1010 disintegrations per second, as the standard curie (Ci).
The curie is used mainly to define quantities of radioactive materials. A curie of an alphaemitter is that quantity which releases 3.7 × 1010 alpha particles per second. A curie of a betaemitter is that quantity of material which releases 3.7 × 1010 beta particles per second, and acurie of a gamma emitter is that quantity of material which releases 3.7 × 1010 photons per sec-ond. The curie represents such a large number of disintegrations per second that the millicurie(mCi), microcurie (μCi), and picocurie (pCi)—corresponding to 10–3, 10–6, and 10–9 curie,respectively—are more commonly used.
The roentgen is a unit of gamma or X-ray radiation intensity. It is of value in the studyof the biological effects that result from ionization induced within cells by radiation. Theroentgen is defined as the amount of gamma or X-ray radiation that will produce in onecubic centimeter of dry air, at 0°C and 760 mm pressure, one electrostatic unit (esu) of
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electricity. This is equivalent to 1.61 × 1012 ions pairs per gram of air and corresponds tothe absorption of 83.8 ergs of energy.
The roentgen is a unit of the total quantity of ionization produced by gamma radiationor X-rays. Dosage rates for these radiations are expressed in terms of roentgens per unit time.
With the advent of atomic energy involving exposure to neutrons, protons, and alphaand beta particles—which also have effects on living tissue—it has become necessary tohave other means of expressing ionization produced in cells. Three methods of expressionhave been used.
The roentgen equivalent physical (rep) is defined as that quantity of radiation (otherthan X-rays or other generated radiation) which produces in one gram of human tissueionization equivalent to the quantity produced in air by one roentgen of radiation or X-rays (equivalent to 83.8 ergs of energy). The rep has been replaced largely by the term rad,which has wider application.
The rad (radiation absorption dose) is a unit of radiation corresponding to an energyabsorption of 100 ergs per gram of any medium. It can be applied to any type and energy ofradiation that leads to the production of ionization. Studies of the radiation of biologicalmaterials have shown that the roentgen is approximately equivalent to 100 ergs/g of tissue;it can be equivalent to 90–150 ergs/g of tissue depending on the energy of the X-ray radia-tion and type of tissue. The rad, therefore, is more closely related to the roentgen than is therep, in terms of radiation effects on living tissues, and is the term biologists prefer.
The rad represents such a tremendous radiation dosage, in terms of permissible amountsfor human beings, that another unit has been developed specifically for humans. The termroentgen equivalent man (rem) is used. It corresponds to the amount of radiation that willproduce an energy dissipation in the human body that is biologically equivalent to one roent-gen of radiation of X-rays, or approximately 100 ergs/g. The recommended maximum per-missible dose for radiation workers is 5 rem/year; for nonradiation workers it is 0.5 rem/year.
RADIOACTIVE CONTAMINANTS IN WATERHumans receive a radiation dose of about 200 millirems (mrem) or 0.2 rem from allsources each year, and the US Environmental Protection Agency (USEPA) estimates thaton average as much as 3 percent of this dose comes from drinking water. Local conditionscan, of course, greatly alter this proportion.
Some of the radioactive substances currently listed for testing as potential drinkingwater contaminants are
• Radium,• Uranium,• Radon, and• Artificial radionuclides.
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RadiumRadium is the most common radionuclide of concern in drinking water. Naturally occur-ring radium leaches into groundwater from rock formations, so it is present in watersources in those parts of the country where there is radium-bearing rock. It may also befound in surface water as a result of runoff from mining and industrial operations whereradium is present in the soil. The three isotopes (variations) of radium of concern in drink-ing water are radium 226, which emits principally alpha particles; radium 228, which emitsbeta particles and alpha particles from its daughter decay products; and radium 224, whichhas a very short half-life of about 3.6 days compared with radium 226 and radium 228,whose half-lives are measured in years. Currently federal regulations ignore radium 224,but some states require monitoring for this isotope even though the sampling, shipping,and testing are difficult to obtain meaningful results.
UraniumNaturally occurring uranium is found in some groundwater supplies as a result of leachingfrom uranium-bearing sandstone, shale, and other rock. Uranium may also occasionally bepresent in surface water, carried there in runoff from areas with mining operations. Ura-nium may be present in a variety of complex ionic forms, depending on the pH of the water.
RadonRadon is a naturally occurring radioactive gas that cannot be seen, smelled, or tasted.Radon comes from the natural breakdown (radioactive decay) of uranium. It is the directradioactive-decay daughter of radium 226. The highest concentrations of radon are foundin soil and rock containing uranium. Significant concentrations, from a health standpoint,may be found in groundwater from any type of geologic formation, including unconsoli-dated formations.
Outdoors, radon emitted from the soil is diluted to such low concentrations that it isnot of concern. However, when it is liberated inside a confined space, such as a home oroffice building, radon can accumulate to relatively high levels, and inhalation of the gas isconsidered a health danger. Most cases of excessive levels of radon in buildings are causedby the gas seeping through cracks in concrete floors and walls. In areas where high levelsof radon in the soil are a problem, foundation ventilation should be installed to reduce theconcentration of radon entering buildings.
The problem from a public water supply standpoint is that, if radon is present in thewater, a significant amount of the gas will be liberated into a building as water is used. Show-ers, washing machines, and dishwashers are particularly efficient in transferring radon gasinto the air. The radon released from the water adds to the radon that seeps into a buildingfrom the soil, adding to the health risk.
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Artificial RadionuclidesSignificant levels of artificial radionuclides have been recorded in surface waters as a resultof atmospheric fallout following nuclear testing, leaks, and disasters. Otherwise, surfacewater generally contains little or no radioactivity. Potential sources of serious water con-tamination are accidental discharges from facilities using radioactive materials, such aspower stations, industrial plants, waste-disposal sites, or medical facilities. State and fed-eral nuclear regulatory agencies monitor all uses of radioactive materials to prevent suchdischarges. If an accidental discharge of artificial radionuclides takes place, the elementsmost likely to be present are strontium 90 and tritium.
ADVERSE HEALTH EFFECTS OF RADIOACTIVITYThe effects of excessive levels of radioactivity on the human body include developmentalproblems, nonhereditary birth defects, genetic effects that might be inherited by futuregenerations, and various types of cancer. All radionuclides are considered to be carcino-gens (cancer-causing agents).
Radium is chemically similar to calcium, so about 90 percent of naturally occurringradium that is ingested goes to the bones. Consequently, the primary risk from radiumingestion is bone cancer. Uranium has not definitely been proven to be carcinogenic yetthe USEPA has set the MCLG at zero, but it accumulates in the bones, much as radium228 does, therefore, as a policy matter USEPA considers uranium a carcinogen. The prin-cipal adverse effect of uranium is toxicity to human kidneys.
Inhaled radon is considered to be a cause of lung cancer. Radon is also thought tohave some noncarcinogenic effects on internal body organs when ingested.
Although the proportion of radon added to a building by the water supply is usuallyrelatively small in comparison with the amount that seeps into the building from the soil,the issue of radon in drinking water is still significant because of the many people beingexposed. USEPA estimates that between 1 and 5 million homes in the United States mayhave significantly high levels of radon contamination and that between 5,000 and 20,000lung cancer deaths a year may be attributed to all sources of radon. USEPA has not set, asof this writing, a maximum contaminant level (MCL) for radon in drinking water.
RADIONUCLIDE MONITORING REQUIREMENTSThe level of restrictions that should be placed on radioactivity in drinking water has beenthe subject of extensive research and much debate. Some experts feel that the requirementsshould be much more restrictive, and others believe the danger is not serious and therequirements should be relaxed.
Another factor that has contributed to the dilemma of regulation is the high cost of radi-onuclide analyses. Although some progress has been made in the form of improved equip-ment and automated operation, analyses still require expensive equipment and trained staffto operate it. The cost is kept as low as possible by requiring an initial scan to determine if
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significant radioactivity is present. Only if the level is higher than a specified point, which isnormally the detection limits for gross alpha or gross beta emitters but can be varied by thedrinking water primacy agency, would it be necessary to progress to further analyses.
Interim RegulationsThe MCLs and monitoring requirements for radionuclides that USEPA promulgated as partof the National Interim Primary Drinking Water Regulations in 1976 were basically as follows:
• Combined radium 226 and radium 228—5 pCi/L.• Gross alpha particle activity (including radium 226 but excluding radon and ura-
nium)—15 pCi/L.• Average annual concentration of beta particle and photon radioactivity from manu-
factured radionuclides—to produce an annual dose equivalent to no greater than4 mrem/year.
Gross alpha particle activity is used as an initial scan, and if it is less than 3 pCi/L, thestate may allow reduced monitoring frequency in the future. If it is more than 3 pCi/L,additional analyses for specific radionuclides are required.
Final Regulation ChangesIn December 2000, USEPA revised the regulations for radionuclides in drinking water. Theproposal suggested some modified as well as some new MCLs for radon and uranium. Thenew standards are shown in Table 8-1. The radon MCL is still being debated at the time ofthis publication (as mentioned in chapter 1 the possible implementation date for radon reg-ulations is 2013 at the earliest.). It is estimated that at least 32,000 community and nontran-sient, noncommunity water systems in the United States will be out of compliance with theradon standard if it is established at the proposed level of 300 pCi/L. Discussion is still tak-ing place on the agreements with the states on the proposed “MMM” or “3M” treatmenttechnique for radon—measure, mitigate and monitor at the points of use.
Sampling began in December 2003 and was based on system size. All systems had tocomplete their initial monitoring by December 31, 2007. To determine the sampling pro-gram for each substance at each entry point, any grandfathered data from June 2000through December 8, 2003, that met the sampling and testing criteria were eligible for use,except data for beta/photon emitters. The new regulations call for sampling each contami-nant at each point of entry at a frequency based on the results of the original quarterlyand subsequent follow-up testing (see Table 8-2).
If a parameter is above the MCL, quarterly sampling must continue until the runningannual average is less than the MCL and all the samples used in the running annual aver-age are below the MCL.
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SELECTED SUPPLEMENTARY READINGSAWWA Inorganics Committee; AWWA Inorganic Contaminants Research Committee.
2009. Committee Report: A Survey of the “Other” Inorganics. Journ. AWWA,101(8):79–86.
Lowry, J.D. 1991. Measuring Low Radon Levels in Drinking Water Supplies. Jour.AWWA, 83(3):149.
Pontius, F.W. 1992. USEPA’s Proposed Radon MCL: Too High, Too Low, or JustRight? Jour. AWWA, 84(10):20.
Pontius, F.W. 1994. Disposal of Radioactive Residuals Requires Careful Planning. Jour.AWWA, 86(11):18.
TABLE 8-1 USEPA’s final regulation for radionuclides in drinking water
Contaminant MCL Notes
Combined radium 226 and 228
5 pCi/L This remains the same as the interim standard of 5 pCi combined radium 226 and 228
Uranium 30 μg/L New standard; based on chemical toxicity so is a weight-based standard
Alpha emitters 15 pCi/L Called adjusted gross alpha; calculated as gross alpha activity minus radium 226 and uranium activity
Beta particle 4 mrem/year Primarily applicable to manufactured radiation and photon emitters
TABLE 8-2 USEPA sampling frequency for radionuclides in drinking water for individual contaminants at each entry point
Frequency Reason
Nine years Results of testing are below the detection limit of approved method
Six years Results of testing are equal to or above the detection limit but equal to or less than one half the MCL
Three years Results of testing are equal to or greater than one half the MCL and equal to or less than the MCL
Quarterly Results of the testing are greater than the MCL
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Radioactivity in Drinking Water. 1991. Criteria and Standards Division, USEnvironmental Protection Agency. Washington, D.C.: USEPA.
Water Quality and Treatment. 6th ed. 2010. New York: McGraw-Hill and AmericanWater Works Association (available from AWWA).
Wong, J.M. 2008. Radioactive! Treating Contaminated Water. Opflow, 34(5):24–27.
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C H A P T E R 9
Customer Inquiries and Complaint Investigation
Responding positively to customers’ inquiries and concerns about water quality can bevery beneficial for water utilities in many ways. The process of responding gives operatorsan additional tool in tracking water quality through the distribution system and determin-ing what customer concerns are. A customer complaint may be an early indication of aquality problem. In addition, customers’ confidence in the quality of the water may bestrengthened by professionally conducted investigations into their concerns.
The previous chapters have established the basis for gathering the data and improvingthe operator’s knowledge of water quality and the effectiveness of the treatment process.These data are also useful in providing customers with the information they need to assurethemselves that the water they are receiving is safe. In addition, the data provide the infor-mation needed to produce the annual consumer confidence report (CCR) as required byregulation (see Chapter 1).
A telephone discussion with—and, if needed, a visit from—a well-informed utilityemployee can certainly improve the utility’s public image for customers. Such discussionsor visits are also opportunities to educate customers regarding the utility’s operations andwater quality.
Water treatment professionals should keep themselves informed not only aboutchanges in regulations and government press releases, but also about any media articlesrelating to possible water quality, such as main breaks, boil-water orders, and outbreaksor potential outbreaks of diseases in the area or nation. This way you will be better pre-pared to handle the questions and concerns of your customers.
GENERAL PRINCIPLESInquiries regarding water quality should be handled promptly and courteously. Many ofthese are health- or aesthetics-related such as the quantity of fluoride, hardness, triha-lomethane levels, or other parameters. Others may be as simple as whether the watersource is surface water or groundwater. These may be driven by a request from a medicalperson for treatment or by news articles or discussions with relatives or friends.
When a complaint is received, an investigation should be undertaken according to thephilosophy that the customer would not be calling if there was not a problem. On average, awater utility receives complaints from approximately less than 1 percent of its customers;thus you may have a larger problem than the number of callers reflects. The problem mightbe real or only perceived; regardless, the customer has a problem and would like it resolved.The caller may be angry, frustrated, embarrassed, or uncomfortable about calling, so the
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receiver of the call should allow the customer to explain the reason for calling before startingto ask questions. Always obtain the customer’s name and address at the beginning of the dis-cussion, which offers reassurance that you are interested and are focused on the area of con-cern. This is a good approach for customers who are in a highly emotional state, because itgives them the opportunity to vent their feelings so they can discuss the subject calmly.
The first order of business is to define the problem. The customer may not know howto explain exactly what is bothering her or exactly what questions to ask. The receivershould repeat to the customer what he has heard: “You said, Mrs. Smith, that the watercoming from your water faucets is brown and has an odor?” or “You indicate that yourfamily is ill from drinking the water?” With the problem established and agreed on, fur-ther questions may be asked to gain details.
Complaint or Inquiry FormIt is helpful for the receiver to have a form to fill out while taking the complaint or inquiry.The form should have three parts:
1. The receiving information, including name, address, phone number, date, and timeand type of complaint.
2. The investigation results, including lab results.3. A description of the final disposition, including the customer’s satisfaction with the
investigation.
InvestigationAlthough it is often difficult, the investigator should approach the problem with an openmind, having no preconceived notions about any part of the investigation. The customershould be asked again to explain the problem, and the investigation should be limited tothat problem only.
In most investigations, water samples should be collected at a cold-water tap beforeany customer treatment, either to confirm the problem or to prove that the water beingdelivered to the premises matches the general condition of the water in the distributionsystem. Temperature and chlorine residual should be tested on-site, and a general chemi-cal sample (hardness, pH, alkalinity, and the like) and a bacteriological sample should becollected for analysis in the lab.
If the solution to the problem is obvious, the customer should be informed immedi-ately. If the solution is the customer’s responsibility, the investigator should advise the cus-tomer about ways and means to implement the solution. If the solution is the utility’sresponsibility, the investigator should advise the customer how the utility will deal withthe problem if possible. If the problem is a perceived one—that is, not really a problem—the investigator must communicate this information tactfully to the customer.
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Final DispositionRegardless of the details of the investigation, the investigator should carry it through to aresolution. The customer should be notified of any laboratory results, kept advised of theinvestigation’s progress, and contacted on its conclusion to ascertain his or her satisfac-tion. The final result should be a satisfied customer. The completed complaint formshould be kept on file for future reference.
SPECIFIC COMPLAINTSA vast majority of complaints fall into one or more of the following categories:
• Objectionable taste and/or odor• Objectionable appearance of the water• Stained laundry and plumbing fixtures• Illness alleged to be caused by the drinking water
Taste and OdorSurveys have shown that taste-and-odor complaints are the type received most frequentlyby most water utilities, especially utilities treating surface waters. Sources of compoundsthat cause taste and odor problems may be natural or may be caused by pollution. Natu-ral compounds result from plant growth including algae or animal activities in the water-shed or source water. Most such natural compounds produce fishy, earthy, or manure-typetastes and odors. Industrial and agricultural/residential discharges into water sources gen-erally produce chemical or medicinal tastes and odors.
Human perceptions of tastes and odors are highly variable. How individuals definewhat they taste and smell depends on many factors, such as the person’s age, health, previ-ous experiences, level of sensitivity, and other senses as they interact with taste and smell.An individual cannot describe an odor as “potato bin” if he/she has not smelled a potatobin. And it is not unusual for an individual to think he/she detects an odor in cloudy orcolored water because of what he/she sees. All these factors make the investigation oftaste-and-odor complaints very tricky.
Receiving informationOnce it has been established that taste and odor are the subjects of a complaint, the cus-tomer should be asked to describe what she/he tastes or smells and what the sourceappears to be—for example, hot or cold faucets, kitchen sink, bathroom sink, or bathtub.It should also be determined at this point if there are customer-owned water treatmentdevices installed in the line and how long the problem has been evident. It is important forthe investigator to know this information.
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InvestigatingThe investigator should try smelling and/or tasting the water from the same faucets inwhich the customer has noticed the condition. To protect the investigator from a possiblecontaminant in the home that could affect his/her health, the recommendation is to smellfirst and taste (using a clean laboratory container) only if the odor is acceptable. If no tasteor odor is detected in the cold water, water from the hot-water system can be tested. Manytaste- and odor-causing compounds are volatile and can be tasted or smelled more readilyfrom hot water. It may also be possible that the taste or odor exists only in the hot water, inwhich case the problem can be immediately located in the residence’s hot-water system.
If a customer detects an odor when it is already known that the water system is experi-encing a taste-and-odor episode, allow the customer to describe the taste or odor to ensureit is from the known condition. In such a case, the source of the problem can be explainedto the customer over the phone. If a customer’s detection of an odor appears to be an iso-lated case, further investigation is required. If the investigation reveals no odor, more inves-tigation may still be necessary to convince the customer that the problem is only aperceived one. In any case, samples should be collected for study at the plant or laboratory.
In conducting the investigation, the investigator should attempt to imagine the manypotential sources of taste and odor. Following is a list of some of the more probable causesand situations.
• A general taste-and-odor incident is occurring in the source water, and the caller is thefirst customer who has complained.
• The customer’s water service is connected to a dead end or to a low-flow main in thedistribution system, and stagnant water is being drawn into the residence’s water service.
• A cross connection has drawn some foreign substance into the water system.• Water system maintenance in the vicinity has stirred up stagnant water or sediment in
the mains.• Waste plumbing or the trap under the sink or bathtub is what is actually causing the
odor problem.• The taste or odor is originating in the hot-water system in the residence.• If a home water conditioner (water softener, carbon filter, or the like) is being used, it
could be causing the problem.• Customers who are in poor health or are elderly may be more inclined to imagine a
problem.• Customers may actually be tasting or smelling something that is not in the water sup-
ply (for example, medication they are taking).• The customer may be noticing the effect of some recent plumbing work in the build-
ing that resulted from a change in piping or from the cleaning solution the plumber orheating contractor used.
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• There may be a cross connection from a sink, garden hose, or flush valve in a toilet, orcontractor in the area may be using a system hydrant and allowing foreign materialinto the customer’s water system.
• Electrical problems may also be causing a problem, either a bad ground in the cus-tomer’s building or something outside the home such as a power utility groundingcondition (after a lightning storm) or from stray current from electrical rail lines, trol-leys, or passenger trains in the area.
• After 9/11, one must also consider that there is the possibility of deliberate contami-nation, which makes the investigation a priority.
Disposition of the complaintAfter the problem has been identified, appropriate action must be taken. If the problem iswithin the jurisdiction of the utility, corrective measures must begin as soon as possible. Ifthe problem is isolated within a residence, the investigator must work with the customer byadvising her/him of the steps she/he can take to eliminate the problem. In all cases, thecustomer must be kept advised of all the steps being taken to solve the problem, includingthe results of any laboratory testing. After the problem has been solved, the customershould be contacted to verify her/his satisfaction with the situation.
Physical AppearanceCustomers generally expect clear, odorless water to be available from their taps at alltimes. When the water deviates from this norm, they become concerned and report theirconcern to the water utility. The physical appearance of water can be affected adversely bysuch things as excess air in the water, sediment from disturbed water lines, rust, particulatematter, bugs, or worms. The latter two have been noted in systems providing drinkingwater from unfiltered surface water supplies (some large cities, because of their watershedprotection programs, are allowed to operate unfiltered surface water systems) or, in thepast, from areas where the finished-water reservoirs are open to the atmosphere. Currentlyall finished-water reservoirs must be covered. A purveyor that has been granted an exemp-tion must provide filtration and disinfection before water from the uncovered reservoirreaches the public.
Receiving informationThe receiver of the complaint call needs to obtain an exact description of the offendingappearance of the water and when the customer first noticed it. On some calls, the receivermay be able to diagnose the problem and offer assistance over the phone, particularly ifthe cause is already known from a previous investigation in the same area or if there is ageneral condition being experienced at the time.
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InvestigatingThe investigator must observe the appearance of the water to develop information fromwhich to draw conclusions and offer solutions. In some cases, it may be necessary to ana-lyze material in the water chemically or under a microscope. When the material and thesource have been identified, the investigator can take steps to correct the problem.
One rather common complaint received by some water systems is that the water is“cloudy” when all it contains is entrained air. Sometimes the callers are new customerswho had not seen entrained air in the water where they lived before, but complaints mayalso come from old customers who may just be noticing the phenomenon for the firsttime. The problem occurs at certain times of the year, especially in cold-weather months,when the water becomes saturated with air. Because a cold pressurized liquid holds moregas than a warm liquid when the water warms in the customer’s building, the “extra” air isreleased, similarly to how it is released from a water heater. When a glass of water is filledbubbles are released, making the water look cloudy when it is fresh from the tap. Thecloudiness quickly clears, though, starting almost immediately at the bottom of the glassand moving upward; the water is completely clear in a minute or so. This cloudiness canalso be the result of a defective faucet aerator or a throttled valve causing a restriction inthe pipeline and a drop in pressure that releases air. Another source of cloudy water canbe bad check valves in air compressors or compressed gas cylinders tied into water linessuch as you would find in medical facilities or food vending locations.
Disposition of the complaintMost complaints of dirty or discolored water due to dissolved or suspended matter in themains can be cleared up by flushing the distribution system and the customer’s plumbing.Regardless, once the problem and source have been identified, the investigator must followthrough to a conclusion. Again, the utility must take action if the problem falls under itsjurisdiction, and the investigator should suggest solutions to the customer if the problemis isolated in the residence.
Staining of Laundry and Plumbing FixturesStaining of laundry and plumbing fixtures can occur when the water contains iron, man-ganese, or copper in solution. It is relatively common for there to be some dissolved ironand manganese.
When a groundwater system pumps directly from wells to the distribution system, thewater is generally clear as it comes from the customer’s tap. However, after the water isexposed to air in a bathtub, toilet, or washing machine, iron oxidizes to red-brown ferrichydroxide precipitate. In some situations iron is partially or completely oxidized in thewater mains, and customers get discolored water either continuously or sporadically.
The iron precipitate causes laundered white clothes to have an off-white color, andbrown stains build up on porcelain fixtures. A particularly exasperating problem for cus-tomers is that, as they repeatedly scour the porcelain fixtures to remove the discoloration,
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they slowly break down the porcelain’s surface glaze, exposing the more porous ceramicbelow; these areas then become discolored even faster and are harder to clean. In this casethere is generally no recourse but to replace the fixtures.
Another common complaint from customers when the iron content is high is that cof-fee and tea turn so dark they look like ink. This darkness is caused by a reaction of theiron with the tannic acid in the beverages.
Manganese is often present with iron in groundwater and may cause similar stainingproblems, except that a dark-brown to black staining precipitate is formed.
Copper staining is usually most objectionable when it creates blue-green stains onplumbing fixtures. Copper staining is caused by aggressive water that dissolves copperfrom the customer’s piping system. Copper release from the customer’s piping can also becaused by stray electrical currents, such as a bad ground or other situation (e.g., an appli-ance or water fountain with electrical cooling); under these conditions the exterior of thecopper piping may develop a black coating.
Receiving informationThe receiver of the complaint call needs to obtain a description of the problem and thecustomer’s location. If the cause is already known from previous complaints, it may bepossible to give the customer advice over the phone about removing the stains or prevent-ing future stains.
InvestigatingIf the complaint is new for the system or for a particular area of the system, the investiga-tor should visit the customer and observe the problem. In some cases, staining can occuras a result of a local problem such as a dead-end main, and special corrective action maybe possible.
Disposition of the complaintIf the problem is only a local condition, it may be possible to correct it by flushing mainsin the area. If the problem recurs regularly in the area, it may be necessary to set up a reg-ular schedule for flushing the mains.
If the problem is found to be general throughout the system, the utility should takesteps to provide treatment to prevent staining from occurring. Methods of iron and man-ganese control are covered in Water Treatment, another book in this series.
Illness Caused by WaterContaminated drinking water can cause illness, and customers generally have been madeaware of this fact through information from educational institutions, the media, or theirdoctor. Some customers call the water utility after visiting a doctor who says that onesource of their illness could be drinking water. Depending on the type of illness, the doctor
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184 WATER QUALITY
or medical facility is obligated to report the findings to health authorities up to andincluding the Centers for Disease Control and Prevention (CDC). The utility may then bedealing with the local, county, state, or federal agency assigned to investigate the allegedincident.
Receiving informationCalls concerning waterborne illness may be some of the most difficult to handle. In manycases, the customer is unsure of terminology and does not know what questions to ask toinitiate the investigation. The receiver of the complaint must be very sensitive in attempt-ing to gain information. Very seldom, with the exceptions of Giardia and Cryptosporidium,will the infectious agent be known.
The chances of illness being caused by contamination of a well-run public water sys-tem are quite remote, but it does happen, so the customer’s complaint cannot be immedi-ately discounted. The receiver needs to determine the symptoms of the illness, the numberof people in the household who are affected, and whether the illness has been diagnosedby a physician. The receiver must be very careful not to sound as if he/she has medicalknowledge when responding to or asking questions.
InvestigatingGenerally, in customer-initiated calls, the customers are seeking to learn whether drinkingwater is a potential source of their illness. The investigator’s job is to provide enough infor-mation that customers can reach their own conclusions regarding water quality.
Even if the person has an illness that is known as a waterborne disease, such as giardi-asis or cryptosporidiosis, the illness could have been contracted through a source otherthan the water system. The vast majority of cases are actually contracted through person-to-person contact, although an occasional case of giardiasis can be traced to a person’scontact with untreated water during a camping or fishing trip.
Nevertheless, a sample for bacteriological analysis should be drawn from a cold-watertap along with a sample for general chemical analysis to set the customer’s mind at ease. Achlorine residual test should be conducted in the presence of the customer and the resultsexplained. The investigator should tell the customer that the bacteriological analysis willdetermine the presence or absence of coliform bacteria and that these coliform bacteria arean indicator for the possibility of pathogenic microorganisms being in the supply. It shouldfurther be explained that the chemical analysis will compare the customer’s tap water withthe water being served to her/him from the distribution system. This will allow the investi-gator to determine whether a problem was occurring in that part of the system or the per-sons residents, possibly a cross connection. An innocent-looking water line penetrating anoutside wall may be connected to an undocumented alternate water source, or possiblycontamination could occur from an unknown customer filter, or mixed plumbing—such asa sprinkler system or treatment device.
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CUSTOMER INQUIRIES AND COMPLAINT INVESTIGATION 185
The investigator should also explain to the customer what precautions are taken toprotect the water supply and how the water is treated by the utility. The customer shouldbe encouraged to consult with a physician if that has not been done.
If investigations indicate the possibility that a waterborne illness is occurring, it isprudent and necessary that the utility notify the primacy agency and possibly also thestate and/or local health departments and request their assistance.
Disposition of the complaintThe results of the bacteriological and chemical analyses should be relayed to the customeras soon as possible and a discussion held as to the customer’s perception of the investiga-tion. The complaint form should be filed for future reference.
SELECTED SUPPLEMENTARY READINGSBurlingame, G.A. 2010. Taste at the Tap – A Consumer’s Guide to Tap Water Flavor.
Denver, CO: American Water Works Association.
Hack, D.J. 1990. Phew! My Hot Water Smells Like Rotten Eggs. Opflow, 16(7):1.
Reinert, R.H. 1992. Quality Is Defined by the Customer. Jour. AWWA, 84(8):20.
Stubbart, J., W.C. Lauer, and T.J. McCandless. 2004. AWWA Water Operator FieldGuide. Denver, CO: American Water Works Association.
Water Quality Complaint Investigator’s Field Guide. 2004. Denver, CO: American WaterWorks Association.
Wert, E. 2003. Solving the Mystery of Green Sand and Water. Opflow, 24(3):18–21.
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187
Glossary
AA See atomic absorption spectrophotometer.
absence See negative sample.
acidity Base neutralizing power.
agar A nutrient preparation used to grow bacterial colonies in the laboratory. Agar ispoured into petri dishes to form agar plates or into culture tubes to form agar slants.
air-strip To remove gases from water by passing large volumes of air through the water.
algae Primitive plants (one- or many-celled) that usually live in water and are capable ofobtaining their food by photosynthesis.
alkalinity Acid neutralizing power.
alpha particle A positively charged particle given off by certain radioactive substances.It consists of two protons and two neutrons and is converted into an atom ofhelium by the acquisition of two electrons.
alum The most common chemical used for coagulation. It is also called aluminum sulfate.
anaerobic Characterized by the absence of air or free oxygen.
analytical balance A sensitive balance used to make precise weight measurements.
anosmia The partial loss or desensitizing of the sense of smell.
apparent color Includes true color and color caused by suspended matter.
aspirate To remove a fluid from a container by suction.
aspirator A T-shaped plumbing fixture connected to a water faucet. It creates a partialvacuum for filtering operations.
atom The basic structural unit of matter; the smallest particle of an element that cancombine chemically with similar particles of the same or other elements to formmolecules of a compound.
atomic absorption spectrophotometer (AA) A spectrophotometer used to determine theconcentration of metals in water and other types of samples.
atomic absorption spectrophotometric method An analytical technique used to identify theconstituents of a sample by detecting which frequencies of light the sample absorbs.
autoclave A device used for sterilizing laboratory equipment by using pressurized steam.
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autoclaved Sterilized with steam at elevated temperature and pressure.
bacterial aftergrowth Growth of bacteria in treated water after the water reaches the dis-tribution system.
balance An instrument used to measure weight.
BAT See best available technology.
beaker A container with an open top, vertical sides, and a pouring lip used for mixingchemicals.
beam balance See single-pan balance.
best available technology (BAT) The best technology, treatment techniques, or othermeans that are available for treatment of a water quality problem and that havebeen found to be practical under field conditions.
beta particle An electron ejected from the nucleus of certain radioactive substances.
biochemical oxygen demand (BOD) A measurement of the amount of oxygen used in thebiochemical oxidation of organic matter over a specified time (usually five days)and at a specific temperature (usually 35°C). Used to indicate the level of con-tamination in water or contamination potential of a waste.
BOD See biochemical oxygen demand.
borosilicate glass A type of heat-resistant glass used for labware.
breakpoint The point at which the chlorine dosage has satisfied the chlorine demand.
breakpoint chlorination The addition of chlorine to water until the chlorine demand hasbeen satisfied and free chlorine residual is available for disinfection.
buffering capacity The capability of water or chemical solution to resist a change in pH.
burette A graduated glass tube fitted with a stopcock, used to dispense solutions duringtitration.
burner A high-temperature-heating device that uses natural or bottled gas. Also called agas burner or Bunsen burner.
calcium carbonate Scale-forming substance in water.
calibrate To adjust a measuring instrument so that it gives the correct result with aknown concentration or sample.
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GLOSSARY 189
carcinogen Any substance that causes cancer.
chlorination The process of adding chlorine to water to kill disease-causing organisms orto act as an oxidizing agent.
chlorine demand The quantity of chlorine consumed by reaction with substances inwater.
Ci See curie.
coagulation The water treatment process that causes very small suspended particles toattract one another and form larger particles. This process is accomplished byadding a chemical, called a coagulant, that neutralizes the electrostatic chargeson the particles that cause them to repel one another.
coliform bacteria A group of bacteria predominantly inhabiting the intestines ofhumans or animals but also occasionally found elsewhere. Presence of the bacte-ria in water is used as an indication of fecal contamination (contamination byhuman or animal wastes).
coliforms (total coliforms) See coliform bacteria.
colony counter An instrument used to count bacterial colonies for the standard platecount test.
color A physical characteristic of water. Color is most commonly tan or brown due tooxidized iron, but contaminants may cause other colors, such as green or blue.Different from turbidity, which is the cloudiness of water. See true color andapparent color for further explanations.
color comparator A device used for tests such as chlorine residual or pH. Concentra-tions of constituents are determined by visual comparison of a permanent stan-dard (usually sealed in glass or plastic) and a water sample.
colorimeter An instrument that measures the concentration of a constituent in a sampleby measuring the intensity of color in that sample. The color is usually created bymixing a chemical reagent with the water sample according to a specific testprocedure.
colorimetric method Any analytical method that measures a constituent in water by deter-mining the intensity of color in the water. The color is usually produced when achemical solution specified by the particular procedure is added to the water.
color unit (cu) The unit of measure of the color of water, measured by comparing thecolor of a water sample with the color of a standard solution.
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combined chlorine residual The chlorine residual produced by the reaction of chlorinewith substances in the water. Because the chlorine is “combined” it is not aseffective a disinfectant as free chlorine residual. In water treatment, this usuallyrefers to compounds formed by the combination of chlorine and ammonia.
community public water system As defined by the National Primary Drinking WaterRegulations, a system that serves at least 15 service connections or at least 25full-time residents 60 or more days per year.
complaint investigation A professionally conducted investigation of a customer’s waterquality complaint.
completed test The third major step of the multiple-tube fermentation method. This testconfirms that positive results from the presumptive test are due to coliform bac-teria. See also confirmed test; presumptive test.
composite sample A series of individual or grab samples taken at different times fromthe same sampling point and mixed together.
compound microscope A microscope with two or more lenses.
confirmed test The second major step of the multiple-tube fermentation method. Thistest confirms that positive results from the presumptive test are due to coliformbacteria. See also completed test; presumptive test.
cross-connection Any connection between a safe drinking water supply and a nonpota-ble water or other fluid. Also called cross-contamination.
C × T value The product of the residual disinfectant concentration C in milligrams perliter, and the corresponding disinfectant contact time T in minutes, or C × T.Minimum C × T values are specified by the Surface Water Treatment Rule as ameans of ensuring adequate kill or inactivation of pathogenic microorganisms inwater.
cu See color unit.
culture tube A hollow, slender glass tube with an open top and a rounded bottom usedin microbiological testing procedures such as the multiple-tube fermentation test.
curie (Ci) The activity of 1 g of radium, or 3.7 × 1010 disintegrations/sec.
cyst A resistant form of a living organism.
D/DBPs See disinfectants–disinfection by-products.
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GLOSSARY 191
deionizer A device used to remove all dissolved inorganic ions from water.
deluge shower A safety device used to wash chemicals off the body quickly.
desiccator A tightly sealed container used to cool heated items before they are weighed.This procedure prevents the items from picking up moisture in the air andincreasing the weight.
dilution bottle A type of heat-resistant glass bottle used for diluting bacteriological sam-ples before analysis. Also called milk dilution bottle or French square.
disinfectants/disinfection By-Products (D/DBPs) A term used in connection with stateand federal regulations designed to protect public health by limiting the concen-tration of either disinfectants or the by-products formed by the reaction of disin-fectants with other substances in the water (such as the natural decompositionproducts of organic matter, leaves, algae, bacteria, etc.).
disposition of complaint An official completion of a complaint investigation, includingan assessment of customer satisfaction.
dissolved oxygen (DO) The oxygen dissolved in water, wastewater, or other liquid, usu-ally expressed in milligrams per liter, parts per million, or percent of saturation.
dissolved solids Any material that is dissolved in water and can be recovered by evapora-tion of the water after filtering the suspended material. Also called filterable residue.
diurnal effect Related to daily activity and daytime hours versus nocturnal events ornighttime hours. Can be seen as a daily pattern or trend (for example, daylightcausing algae to grow, which increases dissolved oxygen and pH while nighttimewill initiate the reverse effect).
DO See dissolved oxygen.
double-pan balance A balance that weighs material by counterbalancing material placedon one pan with brass weights placed on the other pan.
EC See electrical conductivity.
E. coli See Escherichia coli.
EDTA (ethylenediaminetetraacetic acid) A chemical used to sequester, or tie up, calciumand magnesium ions; used in the hardness test.
electrical conductivity (EC) A test that measures the ability of water to transmit electricity.Electrical conductivity is an indicator of dissolved-solids concentration.
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Normally an EC of 1,000 mho/cm2 indicates a dissolved solids concentration of600–700 mg/L.
electrode method Any analytical procedure that uses an electrode connected to a milli-voltmeter to measure the concentration of a constituent in water.
electrophotometer A photometer that uses different colored-glass filters to producewavelengths desired for analyses. Also called a filter photometer.
Enhanced Surface Water Treatment Rule (ESWTR) A revision of the original SurfaceWater Treatment Rule that includes new technology and requirements to dealwith newly identified problems.
equilibrium A balanced condition in which the rate of formation and the rate of con-sumption of a constituent or constituents are equal.
Erlenmeyer flask A bell-shaped container used for heating and mixing chemicals andculture media.
Escherichia coli (E. coli) A bacteria of the coliform group used as a substitute for fecalcoliforms in the regulations of the Total Coliform Rule.
ESWTR See Enhanced Surface Water Treatment Rule.
evaporating dish A glass or porcelain dish in which samples are evaporated to drynessusing high heat.
eyewash A safety device used to wash chemicals from the eyes. One type of deviceresembles a drinking fountain and directs a gentle spray of water into each eye.
fecal coliform A bacteria of the coliform group indicative of fecal contamination. Thepresence of fecal coliform in a water sample is a reportable violation of the TotalColiform Rule.
field blank In organics sampling, a sample created in the field using the same samplecontainer but pouring a sample at the collection site using laboratory-gradeorganic free water to determine if there is any contamination in the air at thesampling location (normally only run if regular sample shows contamination).
filter (laboratory) A porous layer of paper, glass fiber, or cellulose acetate used toremove particulate matter from water samples and other chemical solutions.
filter paper Paper with pore size usually between 5 and 10 μm used to clarify chemicalsolutions, collect particulate matter, and separate solids from liquids.
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GLOSSARY 193
filter photometer See electrophotometer.
filterable residue See dissolved solids.
filtering crucible A small porcelain container with holes in the bottom, used in the totalsuspended solids test. Also known as a Gooch crucible.
flaming The process of passing a flame over the end of a faucet to kill bacteria beforetaking a water sample for bacteriological sampling. The procedure is no longerrecommended because it may damage the faucet and is of questionable benefit.
flask A container, often narrow at the top, used for holding liquids. There are manytypes of flasks, each with its own specific name and use.
flocculation The water treatment process following coagulation that uses gentle stirringto bring suspended particles together so they will form larger, more settleableclumps called floc.
flow-proportional composite A composite sample in which individual sample volumesare proportional to the flow rate at the time of sampling.
free available chlorine residual The residual formed once all the chlorine demand hasbeen satisfied. The chlorine no longer combines with other constituents in thewater and is “free” to kill microorganisms.
French square See dilution bottle.
full-face shield A shatterproof plastic shield worn to protect the face from flying parti-cles and chemicals.
fume hood A large enclosed cabinet equipped with a fan to vent fumes from the labora-tory. Mixing and heating of chemicals are done under the hood to prevent fumesfrom spreading through the laboratory.
funnel A utensil used in the laboratory for pouring liquids into flasks and other contain-ers. Laboratory funnels are either glass or plastic.
gamma ray A form of electromagnetic radiation emitted in nuclear decay.
gas chromatography (GC) A technique used to measure the concentration of organiccompounds in water.
gas chromatography–mass spectrophotometry (GC–MS) A very sophisticated analyticaltechnique for analyzing and identifying organic compounds.
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GC See gas chromatography.
GC–MS See gas chromatography–mass spectrophotometry.
genetic effect A health effect that shows up in subsequent generations.
glass-fiber filter Filters made of uniform glass fibers with pore sizes 0.7 to 2.7 μm. Usedto filter fine particles and algae while maintaining a high flow rate.
Gooch crucible See filtering crucible.
grab sample A single water sample collected at one time from a single point.
graduated cylinder A tall, cylindrical glass or plastic container with quantity graduationmarks on the side and a pouring lip; used for measuring liquids quickly withoutgreat accuracy.
gravimetric procedure Any analytical procedure that uses the weight of a constituent todetermine its concentration.
groundwater under the direct influence of surface water (GWUDI) A term used in stateand federal regulations to designate groundwater sources that are considered vulner-able to contamination from surface water. Systems using such sources must generallyprovide monitoring and treatment as if they were using a surface water source.
GWUDI See groundwater under the direct influence of surface water.
HAA5 Total concentration of the five haloacetic acids. See also haloacetic acids.
half-life (radioactive) The time required for one-half of a radioactive isotope to decay.
haloacetic acids Chemicals formed as a reaction of disinfectants with contaminants inwater, consisting of monochloroacetic acid, dichloroacetic acid, trichloroaceticacid, monobromoacetic acid, and dibromoacetic acid.
hardness A characteristic of water caused primarily by the salts of calcium and magne-sium. Causes deposition of scale boilers, damage in some industrial processes,and sometimes objectional taste; may also decrease the effectiveness of soap.
herbicide A compound, usually a synthetic organic chemical, used to stop or retardplant growth.
heterotrophic plate count (HPC) A laboratory procedure for estimating the total bacte-rial count in a water sample. Also called standard plate count, total plate count, ortotal bacterial count.
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GLOSSARY 195
hot plate An electrical heating unit used in a laboratory to heat solutions.
HPC See heterotrophic plate count.
ICP–MS See inductively coupled plasma – mass spectrometry.
ICR See Information Collection Rule.
incubate To maintain microorganisms at a temperature and in an environment favor-able to their growth.
incubator A heated container that maintains a constant temperature for development ofmicrobiological cultures.
indicator A chemical solution used to produce a visible change, usually in color, at adesired point in a chemical reaction, generally a prescribed end point.
indicator organisms Microorganisms whose presence indicates the presence of fecal con-tamination in water.
inductively coupled plasma–mass spectrometry (ICP–MS) A method for determiningwhat metals are present in a water or wastewater sample using an argon plasma“flame” to ionize the metals and then separate them in the mass spectrometer,which determines the mass (atomic weight) of the substance and the quantitypresent.
Information Collection Rule (ICR) A federal regulation requiring large water systems tocollect special information to build up a database that will assist in the develop-ment of new monitoring and treatment regulations.
inorganic chemical A chemical substance of mineral origin not having carbon in itsmolecular structure.
insecticide A compound, usually a synthetic organic chemical, used to kill insects.
IOC See inorganic chemical.
iodometric method A procedure for determining the concentration of dissolved oxygenin water, also known as the modified Winkler method.
iron bacteria Bacteria that use dissolved iron as an energy source. They can create seri-ous problems in a water system because they form large masses that clog wellscreens, pumps, and other equipment.
ion-exchange resin Beadlike material that removes ions from water; used in deionizers.
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isotopes Varieties of the same element with different masses (different number of neutrons).
jar test apparatus An automatic stirring machine equipped with three to six paddles anda variable-speed-motor drive. Used to conduct the jar test for evaluating thecoagulation, flocculation, and sedimentation processes.
labware Any of a variety of laboratory equipment—whether plastic, glass, metal orother material—used in the preparation and analysis of samples in a laboratory.
Langelier saturation index (LSI) A numerical index that indicates whether calcium car-bonate will be deposited or dissolved in a distribution system. The index is a gen-eral indicator of the corrosivity of water.
magnetic stirrer A device used for mixing chemical solutions in the laboratory.
maximum contaminant level (MCL) The maximum permissible level of a contaminant inwater as specified in the regulations of the Safe Drinking Water Act.
maximum contaminant level goal (MCLG) Nonenforceable health-based goals pub-lished along with the promulgation of an MCL. Originally called recommendedmaximum contaminant levels (RMCLs).
maximum residual disinfectant level (MRDL) The maximum free chlorine, chloramine,and chlorine dioxide residual allowable in distribution-system water.
MCL See maximum contaminant level.
MCLG See maximum contaminant level goal.
membrane filter A filter made of cellulose acetate with a uniform small pore size. Usedfor microbiological examination.
membrane filter (MF) method A laboratory method used for coliform testing. The pro-cedure uses an ultrathin filter with a uniform pore size smaller than bacteria—less than a micron. After water is forced through the filter, the filter is incubatedin a special media that promotes the growth of coliform bacteria. Bacterial colo-nies with a green-gold sheen indicate the presence of coliform bacteria.
meter An instrument (usually electronic) used to measure water quality parameters suchas pH.
methyl orange An indicator used in the measurement of the total alkalinity of a watersample.
mg/L See milligrams per liter.
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GLOSSARY 197
mho (Ω-1) A unit of conductance equivalent to the reciprocal of the ohm. This can bemeasured on a mhometer.
microbiological Relating to microorganisms and their life processes.
milk dilution bottle See dilution bottle.
milligrams per liter (mg/L) A unit of the concentration of a water or wastewater constit-uent: 0.001 g of the constituent in 1,000 mL of water. In reporting the results ofwater and wastewater analysis it has generally replaced parts per million, towhich it is approximately equivalent.
MMO–MUG technique An approved bacteriological procedure for detecting the pres-ence or absence of total coliforms.
modified Winkler method A modification of the standard Winkler (iodometric) methodthat uses an alkali-iodide-azide reagent to make the procedure less subject tointerferences.
Mohr pipette A pipette with a graduated stem used to measure and transfer liquidswhen great accuracy is not required.
monitoring Routine observation, sampling, and testing of water samples taken from dif-ferent locations within a water system to determine water quality, efficiency oftreatment processes, and compliance with regulations.
mottled Spotted or blotched. Teeth can become mottled if excessive amounts of fluorideare consumed during the years of tooth formation.
MRDL See maximum residual disinfectant level.
muffle furnace A high-temperature oven used to ignite and burn volatile solids, usuallyoperated at temperatures near 600°C.
multiple-tube fermentation (MTF) method A laboratory method used for coliform test-ing that uses a nutrient broth placed in culture tubes. Gas production indicatesthe presence of coliform bacteria.
mutagen A substance that can change the structure of deoxyribonucleic acid (DNA)and thus change the basic blueprint for cell replication.
National Primary Drinking Water Regulations (NPDWRs) Regulations developed underthe Safe Drinking Water Act. The regulations establish maximum contaminantlevels, monitoring requirements, and reporting procedures for contaminants indrinking water that endanger human health.
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natural radioactive series A sequence of elements that exist naturally and decay intoeach other in a serial fashion.
negative sample When referring to the multiple-tube fermentation or membrane filtertest, any sample that does not contain coliform bacteria. Also called absence.
nephelometer An instrument that determines turbidity by measuring the amount of lightscattered by turbidity in a water sample. It is the only instrument approved bythe US Environmental Protection Agency to measure turbidity in treated drink-ing water.
nephelometric turbidimeter See nephelometer.
nephelometric turbidity unit (ntu) The amount of turbidity in a water sample as mea-sured using a nephelometer.
neurotoxic Having a poisonous effect on nerve tissue.
nomographic method A method that uses a graph or other diagram to solve formulasand equations.
nontransient, noncommunity public water system A system having its own water supplyand serving an average of at least 25 persons who do not live at the location butwho use the water for more than six months per year.
NPDWRs See National Primary Drinking Water Regulations.
ntu See nephelometric turbidity unit.
Office of Ground Water and Drinking Water (OGWDW) The office within the US Envi-ronmental Protection Agency having responsibility for the administration of theSafe Drinking Water Act.
Ohm (Ω) A unit of resistance measured on an ohmmeter.
opportunistic bacteria Several types of bacteria that are not usually a danger to personsin good health but can cause sickness or death in persons who are in a weakenedcondition.
organic chemical A chemical substance of animal or vegetable origin having carbon inits molecular structure.
oven A chamber used to dry, burn, or sterilize materials.
oxidant Any chemical substance that promotes oxidation.
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GLOSSARY 199
oxidize To chemically combine with oxygen.
P–A test See presence–absence test.
parts per million (ppm) The number of weight or volume units of a constituent presentwith each one million units of the solution or mixture. Formerly used to expressthe results of most water and wastewater analyses but being replaced by milli-grams per liter. For drinking water analysis, concentrations in parts per millionand milligrams per liter are equivalent.
pathogens (pathogenic) Disease-causing organisms.
pCi See picocurie.
petrie dish A shallow glass or plastic dish with vertical sides, a flat bottom, and a loose-fitting cover. Used for growing microbiological cultures.
pH A measure of water’s acidity or alkalinity. A scale of 0 to 14 is used, with 0 beingextremely acidic and 14 being extremely alkaline.
phenanthroline method A colorimetric procedure used to determine the concentration ofiron in water.
phenolphthalein indicator A chemical color-changing indicator used in several tests,including tests for alkalinity, carbon dioxide, and pH.
pH meter A sensitive voltmeter used to measure the pH of liquid samples.
photometer An instrument used to measure the intensity of light transmitted through asample or the degree of light absorbed by a sample.
pHs – pH of saturation. The theoretical pH at which calcium carbonate will neither dis-solve nor precipitate. Used to calculate the Langelier saturation index.
picocurie (pCi) The measurement of radioactivity most often used in drinking water
standards, equal to 10–12 Ci.
pipette Slender glass or plastic tube used to measure and transfer small volumes (usuallyless than 25 mL) of liquids.
platinum–cobalt method A procedure used to determine the amount of color in water.
PN See public notification.
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point-of-use (POU) treatment A water treatment device used by a water customer totreat water at only one point, such as at a kitchen sink. The term is also some-times used interchangeably with “point-of-entry treatment” to cover all treat-ment installed on customer services.
positive sample In reference to the multiple-tube fermentation or membrane filter test,any sample that contained coliform bacteria. Also called presence.
potentiometric method Any laboratory procedure that measures a difference in electricpotential (voltage) to indicate the concentration of a constituent in water.
POU treatment See point-of-use treatment.
ppm See parts per million.
precipitate To separate a substance from a solution or suspension by a chemicalreaction.
precursor compound Any of the organic substances that react with chlorine and otherdisinfectors to form trihalomethanes and other disinfection by-products.
presence See positive sample.
presence–absence (P–A) test An approved bacteriological procedure for the detection oftotal coliforms. The results are qualitative rather than quantitative.
presumptive test The first major step in the multiple-tube fermentation test. The steppresumes (indicates) the presence of coliform bacteria on the basis of gas produc-tion in nutrient broth after incubation.
primary enforcement responsibility or primacy The acceptance by federal government,states or other government entity, regional body, or tribal unit of the responsibil-ity for enforcing the Safe Drinking Water Act requirements.
probe method See electrode method.
progeny The various new elements that are formed as a result of transmutation of aradioactive substance.
protozoa Small, single-cell animals, including amoebas, ciliates, and flagellates.
public notification (PN) A required notice to the public given by water systems that vio-late operating, monitoring, or reporting requirements.
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GLOSSARY 201
public water system (PWS) As defined by the Safe Drinking Water Act, any system,publicly or privately owned, that serves at least 15 service connections 60 daysout of the year, or serves an average of 25 people at least 60 days out of the year.
PWS See public water system.
QA See quality assurance.
QC See quality control.
quality assurance (QA) A program to ensure consistency in analytical results betweenlaboratories by periodically testing each laboratory through the analyses of aprecisely prepared blind sample.
quality control (QC) A laboratory program of continually checking techniques and cali-brating instruments to ensure consistency in analytical results.
rad A measure of the dose absorbed by the body from radiation (100 ergs of energy in 1 gof tissue). The abbreviation stands for radiation absorbed dose.
radioactive decay A process by which the nucleus of an atom transforms to a lowerenergy state by emitting alpha, beta, or gamma radiations.
radionuclide A material with an unstable atomic nucleus that spontaneously decays ordisintegrates, producing radiation.
reagent bottle A bottle made of borosilicate glass fitted with a ground-glass stopper,used to store reagents (standard chemical solutions).
recarbonation The process of adding carbon dioxide as a final stage in the lime–soda ashsoftening process to convert carbonate to bicarbonates. This process preventsprecipitation of carbonates in the distribution system.
receiver The water treatment system staff member taking information from a customerregarding a water quality complaint.
reg-neg See regulatory negotiation process.
regulatory negotiation process (reg-neg) A US Environmental Protection Agency pro-cess drawing on the experience of many people in the water works field to “nego-tiate” the various issues in preparing a new draft regulation for public comment.
rem A quantification of radiation in terms of its dose effect on the human body; thenumber of rads times a quality factor. The abbreviation stands for radiationequivalent man.
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202 WATER QUALITY
representative sample A sample containing all the constituents that are in the water fromwhich it was taken.
routine (required) sample A sample required by the National Primary Drinking WaterRegulations to be taken at regular intervals to determine compliance with themaximum contaminant levels.
Safe Drinking Water Act A federal law enacted December 16, 1974, setting up a cooper-ative program among local, state, and federal agencies to ensure safe drinkingwater for consumers.
sample bottle A wide-mouth glass or plastic bottle used for taking microbio logical andchemical water samples.
SDWA See Safe Drinking Water Act.
Secondary Drinking Water Regulations Regulations developed under the Safe DrinkingWater Act that establish maximum levels for substances affecting the taste, odor,or color (aesthetic characteristics) of drinking water.
selective absorption A method used in gas chromatography to separate organic com-pounds so their concentrations can be determined.
sequestering A chemical reaction in which certain chemicals (sequestering or chelatingagents) “tie up” other chemicals, particularly metal ions, so that the chemicals nolonger react. Sequestering agents are used to prevent the formation of precipi-tates or other compounds.
siemens (s) A unit of conductance equal to 1 ampere per volt.
single-pan balance A balance used to make quick, accurate weight measurements. Thematerial to be weighed is placed on the pan, and counterweights located on arms(beams) beneath the pan are adjusted to balance the material, thus indicating theweight. Also known as a beam balance.
SOCs See synthetic organic chemicals.
sodium hypochlorite A solution of chlorine dissolved in a diluted sodium hydroxidesolution used as a source of chlorine in water treatment. The chemical formula isNaOCl. Also known as bleach. In old literature the term Javel (Javelle) watermay be used.
solid phase microextraction (SPME) A procedure used in the preparation of samples fororganic analysis in a gas chromatograph using a small treated column “filter” todirectly extract from the liquid the compounds to be analyzed. The compound
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GLOSSARY 203
extracted is determined by the coating on the SPME “filter,” which is then placedin the GC–MS for thermal desorption. The quantity of the substance present isdirectly related to the concentration of the substance in the sample. Readings inthe parts-per-trillion levels are possible. The method can speed analysis time byup to 70% because of the direct extraction without the use of solvents.
SPADNS method A colorimetric procedure used to determine the concentration of flu-oride ion in water. SPADNS [sodium 2-(parasulfophenylazo) 1.8-dihydroxy-3,6-naphthalene disulfonate] is the chemical reagent used in the test.
specific-ion meter A sensitive voltmeter used to measure the concentration of specificions (e.g., fluoride) in the water. Electrodes designed specifically for each ionmust be used.
spectrophotometer A photometer that uses a diffraction grating or a prism to control thelight wavelengths used for specific analysis.
splash goggles Safety goggles with shatterproof lenses designed to provide a tight cover-ing around the eyes, protecting them from chemicals and flying particles.
SPME See solid phase microextraction.
stable Resistant to change.
Surface Water Treatment Rule (SWTR) A federal regulation established by the USEnvironmental Protection Agency under the Safe Drinking Water Act thatimposes specific monitoring and treatment requirements on all public drinkingwater systems that draw water from a surface water source.
SWTR See Surface Water Treatment Rule.
synthetic organic chemicals (SOCs) Generally applied to manufactured chemicals thatare not as volatile as volatile organic chemicals. Included are herbicides, pesti-cides, and chemicals that are widely used in industries, such as ethylbenzene,styrene, and toluene.
TCR See Total Coliform Rule.
TD A mark on a pipette meaning “to deliver.” The pipette is calibrated to deliver thecalibrated volume of the pipette with a small drop left in the tip.
teratogenic effect A health effect on a fetus.
test tube A slender glass or plastic tube with an open top and rounded bottom. Used fora variety of tests.
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204 WATER QUALITY
THMs See trihalomethanes.
threshold odor number (TON) A number indicating the greatest dilution of a water sam-ple (using odor-free water) that still yields a noticeable odor.
time composite A composite sample consisting of several equal-volume samples taken atspecified times.
titration A method of analyzing the composition of a solution by adding knownamounts of a standardized solution until a given reaction or end point (colorchange, precipitation, or conductivity change) is produced.
titrimetric method Any laboratory procedure that uses titration to determine the con-centration of a constituent in water.
TOC See total organic carbon.
TON See threshold odor number.
Total Coliform Rule (TCR) A regulation that became effective December 31, 1990, doingaway with the previous maximum contaminant level relating to the density oforganisms and relating only to the presence or absence of the organisms in water.
total coliform test Either the multiple-tube fermentation or the membrane filter test.Both tests indicate the presence of the entire coliform group, or total coliforms.
total organic carbon (TOC) The results of a general analysis performed on a water sam-ple to determine the total organic content of the water.
total trihalomethanes (TTHMs) The total of the concentrations of all the triha-lomethane compounds found in the analysis of a water sample.
toxic Causing an adverse effect on various body parts (such as the liver or kidneys).
transect An imaginary line along which samples are taken at specified intervals. Transectsampling is usually done on large bodies of water such as rivers and lakes.
transfer pipette See volumetric pipette.
transient, noncommunity public water system An establishment having its own water sys-tem, where an average of at least 25 persons per day visit and use the water occa-sionally or for only short periods of time.
transmutation The changes that take place in a radioactive substance due to radioactivedisintegration.
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GLOSSARY 205
trihalomethanes (THMs) A group of compounds formed when natural organic com-pounds from decaying vegetation and soil (such as humic and fulvic acids) reactwith chlorine.
trip blank In organics sampling, a sample container prepared in the laboratory withlaboratory-grade organics-free water. The container travels with the sample col-lector throughout the sample run and is returned to the laboratory to determineif contamination was present in the laboratory or any equipment used in thesampling process.
true color The color of water from which turbidity has been removed.
TTHMs See total trihalomethanes.
turbidimeter An instrument that measures the amount of light impeded or scattered bysuspended particles in a water sample, using a standard suspension as a reference.
turbidity A physical characteristic of water that makes the water appear cloudy. Thecondition is caused by the presence of suspended matter.
URTH See unreasonable risk to health.
US Environmental Protection Agency (USEPA) A US government agency responsiblefor implementing federal laws designed to protect the environment. Congress hasdelegated implementation of the Safe Drinking Water Act to the USEPA.
USEPA See US Environmental Protection Agency.
USPHS See US Public Health Service.
US Public Health Service (USPHS) A government agency that established early stan-dards for acceptable drinking water quality under provisions of the InterstateQuarantine Act of 1893.
utility oven A laboratory oven used primarily to dry labware and chemicals prior toweighing or to sterilize labware.
vacuum pump A pump used to provide a partial vacuum; needed for filtering operationssuch as the membrane filter test.
viable Capable of living.
VOCs See volatile organic chemicals.
volatile organic chemicals (VOCs) Lightweight organic compounds that vaporize easily.
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206 WATER QUALITY
volumetric flask A squat bottle with a long, narrow neck used to prepare fixed volumesof solution. Each flask is calibrated for a single volume only.
volumetric pipette A pipette calibrated to deliver a single volume only.
water still A device used to produce distilled water by evaporation and condensation oftap water.
waterborne disease Any illness caused by a pathogenic organism carried by water.
zeta potential The resistance between suspended particles in water.
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Index
Aacidity 125measurements of 125
significance 125total acidity 125
action levels 32alkalinity 126, 127
coagulants 127types of 126
amperometric titration 152Arsenic Rule 34artificial radionuclides 175
Bbacteria
in water 111opportunistic bacteria 111
balances 94best available technology (BAT) 1breakpoint 149breakpoint chlorination 149
CC × T value 28calcium carbonate stability 127
Langelier Saturation Index (LSI) 127marble test 127Ryzner Index 127sampling 128significance 127
calibration curve 99Campylobacter 111carbon dioxide 147
carbonic acid 147sampling 147significance 147
carcinogens 4, 165chain of custody 64
field log sheet 64record keeping 64sampling
sampler’s liability 64sampler’s responsibility 64
chlorination 148chlorine
combined chlorine residual 149combined residual 148demand 148, 150, 152distribution system sampling 151DPD method 152free available residual 148residual 148, 151significance 148
treatment plant sampling 151coagulants 127, 130, 131coagulation 130, 131coagulent effectiveness 129
coagulants 130, 131coagulation and flocculation 130jar test 130particle counters 133particle counting 133sampling 130significance 130streaming current detector (SCD) 132zeta potential 131
zeta meter 132coliform bacteria 113, 120
coliform analyses 114presence–absence (P-A) method 114test methods 114
alternate methods 120completed test 117confirmed test 117E. coli procedure 119fecal coliform procedure 119membrane filter (MF) method 120MMO–MUG technique 119multiple-tube fermentation (MTF)
method 114coliform bacteria (cont’d)
presence–absence (P-A) test 119presumptive test 114ten-tube procedure 119
coliforms 24colloids 131color of water 134
apparent color 134color unit 134platinum–cobalt method 135sampling 135significance 134true color 134
colorimeters 97conductivity 135
sampling 136significance 135
consumer confidence report (CCR) 30Consumer Confidence Report Rule (CCR Rule) 36
information 36timetable 36
contaminantschemical monitoring requirements 59chemicals 58
copperstaining 185
corrosion 127, 147, 157control 32, 128
Cryptosporidium 2, 27, 29, 30, 109, 112, 186
207
208 WATER QUALITY
prevention 113customer inquiries and complaint investigation 179
final disposition 181illness 185–187inquiry form 180investigation 180physical appearance 183staining 184taste and odor 181–183
DDisinfectant/Disinfection By-Products (D/DBP)
Rule 129disinfectants 34disinfection by-products 34Stage 1 34Stage 2 35
disinfection 27, 28disinfection by-products (DBPs) 150, 162
sampling 150dissolved oxygen (DO) 152
sampling 153significance 152Winkler method 153
Distribution System Rule 25diurnal effect 42Drinking Water Contaminant Candidate List
(DWCCL) 26
EE. coli 30, 111, 119, 120electrical conductivity (EC) 97electrophotometers 99Enhanced Surface Water Treatment Rule
(ESWTR) 144equilibrium point 127
FFederal Register 38Filter Backwash Recycling Rule (FBRR) 31filtration 27, 28, 143five haloacetic acids (HAA5) 150flash mixing 130floc 127, 131flocculation 130, 131fluoride 155
electrode method 156fluoride concentrations 156sampling 156significance 155SPADNS method 156tooth decay 155
Ggas chromatography 166
concentration 166detection 166detector 166extraction 166gas chromatograph 166separation 166
gastroenteritis 25Giardia 186Giardia lamblia 26, 27, 112giardiasis 112Ground Water Rule (GWR) 26, 35, 44groundwater 35
Hhardness 136
EDTA method 137hard water 136sampling 137significance 136soft water 136
hepatitis A virus (HAV) 112heterotrophic plate count (HPC) procedure 120
performing procedure 122uses 120
hydrocarbons 161, 162
Iillness 185
complaint disopsition 187complaint investigation 186
inorganic chemicals 147carbon dioxide 147chlorine demand 148chlroine residual 148disinfection by-products 150dissolved oxygen 152fluoride 155inorganic metals 153inorganic nonmetallic compounds 155iron 156manganese 157pH 158
inorganic metals 153methods of determination 154sample preservation 153, 154sampling 153sources of contamination 154
inorganic nonmetallic contaminants 155Interim Enhanced Surface Water Treatment Rule
(IESWTR) 29iron 156
INDEX 209
absorption spectrophotometric (AA) method 157
Inductively Coupled Plasma (ICP) analysis 157
iron bacteria 157phenanthroline method 157red water 157significance 157
Jjar test 130Journal of the American Water Works
Association 38
Llaboratory certification 59laboratory equipment and instruments 67
analytical laboratory instruments 94–106aspirators 90balances 94–97
laboratory equipment (cont’d)analytical balances 95digital balances 95double-pan balances 94locations 95pan balance 94rough balance 94single-pan balances 94
beakers 68Biochemical Oxygen Demand bottles 71burettes 68
bottle-top burette 68burners 92
gas burner 92cleaning labware 77colony counters 78culture tubes 77deionizers 90deluge/safety showers 86desiccators 78dilution bottles 69evaporating dishes 75eye protection 86
chemical splash goggles 86eyewashes 86full-face shields 86
filtering crucibles 75filters 92
filter paper 93glass-fiber filters 93membrane filters 93
fire blanket 87fire extinguishers 86
flasks 69Erlenmeyer flasks 71volumetric flasks 71
fume hoods 78funnels 71gas chromatographs 106graduated cylinders 71hot plates 91incubators 80
dry-heat incubators 81low-temperature incubators 81mechanical-convection incubators 81water-bath incubators 82
jar test apparatus 82labware 67–77
heat-resistant glass 67plastic 67soft (nonheat-resistant) glass 67
magnetic stirrers 93major laboratory equipment 78–85membrane filter apparatus 82meters 97–103
atomic absorption spectrophotometer 100
calibration curve 99color comparators 97colorimeters 97electrical conductivity meters 97electrophotometers 99nephelometric turbidimeters 102, 103pH meters 100photometers 97plasma–mass spectrometry 100specific-ion meters 101spectrophotometers 100, 106turbidimeters 102
microscopes 103compound microscope 104wide-field dissecting microscope 103
ovens 83autoclaves 83muffle furnaces 83utility ovens 83
petri dishes 72pipettes 73
measuring pipettes 73Mohr pipettes 74serological pipettes 73transfer pipettes 74volumetric pipettes 73, 74
polycarbonate cylinders 71porcelain dishes 75reagent bottles 75refrigerators 84safety equipment 86–90sample bottles 76
210 WATER QUALITY
support equipment 90–94test tubes 77vacuum pumps 94water stills 90, 91
Langelier Saturation Index (LSI) 127, 128, 141Lead and Copper Rule 31, 50, 135, 136, 141
corrosion control 32lead and copper 31lead and copper, health effects of 31source water 32
Legionella 26, 27, 111Legionnaires’ disease 28lifetime distribution system evaluation (LDSE) 35liquid–liquid extraction 166Locational Running Annual Average (LRAA) 35Long-Term 1 Enhanced Surface Water Treatment
Rule (LT1ESWTR) 29Long-Term 2 Enhanced Surface Water Treatment
Rule (LT2ESWTR) 30
Mmanganese 157
AA method 158ICP mass spectroscopy (ICPMS) 158sampling 158significance 158staining 158, 185
marble test 127maximum contaminant level goal (MCLG) 5maximum contaminant levels (MCL) 4, 5maximum residual disinfectant level goal
(MRDL/MRDLG) 5membrane filter (MF) method 120meniscus 67microbiological contaminants 109
bacteria 111coliform analyses 114coliform bacteria 113epidemics 109heterotrophic plate count (HPC)
procedure 120indicator organisms 113–120opportunistic bacteria 111protozoa 112sampling 114test methods 114viruses 111waterborne diseases 110, 112waterbourne diseases 109
millivolt scale 100MMO–MUG technique 119multiple-tube fermentation (MTF) method 114
NN,N-diethyl-p-phenylenediamine (DPD) test
kit 151National Primary Drinking Water Regulations
(NPDWRs) 1, 4, 49National Secondary Drinking Water
Regulations 22nitrate 155noncarcinogens 164
OOptimal Corrosion Control 32organic chemicals
carcinogens 165health effects 164measurement 106, 165–168
general analytical methods 165specific analytical methods 166total organic carbon (TOC) 165total organic halogen (TOX) 166
noncarcinogens 164organic compounds 163
sampling 167See also organic contaminants
organic contaminants 161algae 163disinfection by-products 163humic materials 161in groundwater 161in surface water 163microorganisms 163natural organic substances 161synthetic organic substances 164THMs 163
Pparticle counters 133pH 158
importance 159pH meters 100
combined/combination electrode 101millivolt scale 100scales 100
photometers 97physical appearance of water
complaint disposition 184complaint investigation 184complaints 183
presence–absence (P-A) test 119primacy 1primary enforcement responsibility
See primacyProposed Radon in Drinking Water Rule 37
INDEX 211
protozoa 112Cryptospridium 112Giardia lamblia 112
public water systems 2classification 4community public water systems (CWS) 3nontransient, noncommunity public water
systems (NTNCWS) 3transient, noncommunity public water systems
(TNCWS) 3
Rradiation 171radioactive contaminants 171
alpha particles 171artificial radionuclides 175beta radiation 172gamma radiation 172in water 173radium 174radon 174uranium 174
radioactivityelectrons 172final regulation changes 176gross alpha particle activity 176health effects 175interim regulations 176photons 172radioactive atom 171radioactive materials 171radionuclide monitoring requirements 175unit of measurement 172
curies 172radiation absorption dose (rad) 173roentgen 172roentgen equivalent man (rem) 173roentgen equivalent physical (rep) 173standard curie 172
Radionuclides Rule 30radium 174, 175radon 174, 175red water 157regulations
action level 32Arsenic Rule 34Consumer Confidence Report Rule (CCR
Rule) 36contaminants 4, 26current and future rules 23–33Disinfectant/Disinfection By-Products
(D/DBP) Rule, Stage 1 34Disinfectant/Disinfection By-Products
(D/DBP) Rule, Stage 2 35Drinking Water Contaminant Candidate List
(DWCCL) 26drinking water program requirements 33exemptions 20Filter Backwash Recycling Rule (FBRR) 31grandfathering 2Ground Water Rule (GWR) 35laboratories 59Lead and Copper Rule 31legal limits 1, 25Long-Term 1 Enhanced Surface Water
Treatment Rule (LT1ESWTR) 29Long-Term 2 Enhanced Surface Water
Treatment Rule (LT2ESWTR) 30maximum contaminant level goals 5maximum contaminant levels (MCLs) 4, 5maximum residual disinfectant level goal
(MRDL/MRDLG) 5monitoring 20monitoring and reporting requirements 20National Primary Drinking Water Regulations
(NPDWRs) 1, 4National Secondary Drinking Water
Regulations 22online resources 37Optimal Corrosion Control 32primacy 1Proposed Radon in Drinking Water Rule 37public notification 18–20public water supply 1public water systems 2–4Radionuclides Rule 30record keeping 20, 33reporting 20, 33Safe Drinking Water Act 1sampling and testing 20SDWA amendments 2standardized monitoring framework 20Surface Water Treatment Rule 26–29Tier violations
Tier I 18Tier II 18Tier III 18
Total Coliform Rule 24Unregulated Contaminant Monitoring Rule
(UCMR) 26US Environmental Protection Agency
regulations (cont’d)(USEPA) 1variances 20violations 18Water Quality Parameters 33
roentgen 172running annual averages (RAA) 5Ryzner Index 127
212 WATER QUALITY
SSafe Drinking Water Act 164Safe Drinking Water Act (SDWA) 1Salmonella 111sampling 114
bacteriological sample points 53calcium carbonate stability 128carbon dioxide 147chlorine residual samples 51coagulent effectiveness 130coliform analysis 52collection 55collection procedures
distribution system 56special testing purposes 58treatment plant 56
color 135conductivity 136containers 55contaminants 50customer faucets 54dead-end sampling points 54disinfection by-products 150dissolved oxygen 153dissolved oxygen (DO) 42distribution system sampling 151fluoride 156hardness 137holding times 62importance 41inorganic metals 153in-plant sample points 48–49iron 157manganese 158organic compounds 167preservation 62problems 63raw-water sample collection procedures 55record keeping 61sample
labeling 61locations 48points 50taps 47, 56
sample cock 44sample faucets 54, 59sample-point locations 52sample-preservation techniques 62sampling frequency 50sampling point selection 44
distribution system 49groundwater 45groundwater sources 44raw-water sample point 44raw-water transmission lines 44
reservoirs and lakes 46, 47rivers 46treatment plant 47
storage 62taste and odor 138temperature 141time of sampling 62total dissolved solids (TDS) 42transportation 63
shipment 63treatment plant sampling 151turbidity 143turbidity sample 52types of samples 41–44
composite samples 43continuous samples 43grab samples 41
well sampling 46scale formation 136
See also calcium carbonate stabilityScience Advisory Board (SAB) 109Shigella 111SPADNS method 156specific-ion meters 101spectrophotometers 100, 106staining 184
complaint disposition 185complaint investigation 185
standardized monitoring framework 20streaming current detector (SCD) 132Surface Water Treatment Rule 26, 129, 151
C × T values 28disinfection 27disinfection residual 29filtration 27, 28groundwater 27requirements 29surface water 27treatment technique 27turbidity 29waterbourne disease 27
surface-water 41synthetic organic chemicals (SOCs) 164
Ttaste and odor in water 137
complaint disposition 183complaint investigation 182complaints 181flavor profile analysis 140odor test 138sampling 138significance 138threshold odor number (TON) 138threshold odor test 139
INDEX 213
temperature 141sampling 141significance 141thermometer 141
threshold odor number (TON) 138, 139Tier violations 18titration 68total acidity 125Total Coliform Rule (TCR) 24, 119, 129
coliforms 24gastroenteritis 25legal limit 25MCL violation 25
total dissolved solids 142significance 142
total filterable residueSee total dissolved solids
total organic carbon (TOC) 35, 131, 165total organic halogen (TOX) 166total trihalomethane (TTHM) 34trihalomethanes 150turbidimeters 102, 133
nephelometric turbidimeters 102, 103, 144turbidity 130, 131, 142
nephelometric turbidimeter 144nephelometric turbidity units (ntu) 143sampling 143sampling points 144significance 143
UUnregulated Contaminant Monitoring Rule
(UCMR) 26uranium 174, 175US Environmental Protection Agency (USEPA) 1
Vviruses 111
hepatitis A virus (HAV) 112volatile organic chemicals (VOCs) 164
Wwater properties 125
acidity 125alkalinity 126calcium carbonate stability 127coagulent effectiveness 129color 134conductivity 135floc 127hardness 136taste and odor 137temperature 141total dissolved solids 142turbidity 142
water quality 41Water Quality Association 38water quality monitoring 41
chain of custody 64chemical contaminant monitoring 59
analytical techniques 59chemical contaminants 58groundwater 41laboratories 59–61record keeping 61sample labeling 61sampling 41–58
Water Quality Parameters 33waterbourne diseases 27, 109, 110, 112
health risks 110waterbourne illness 186Winkler method 153
Zzeta meter 132zeta potential 131
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