domestic rain water harvested water quality : an overview

DOMESTIC RAIN WATER HARVESTED (DRWH) WATER QUALITY: An

Overview

BLESSY V. A.M. Sc. (WST)Roll No. 50009

“Earth provides enough to satisfy human needs, but not a single man’s greed”

-Mahatma Gandhi

- Water scarcity is the lack of sufficient available water resources to meet water needs within a region

- It affects every continent and around 2.8 billion people. More than 1.2 billion people lack access to clean drinking water.

- Making water available in the desired quantity and quality, at the right time and place is a challenge before water professional

Source:United nations development programme, 2013.

How we can overcome water scarcity?

• Rain water harvesting

• Waste water treatment

• Transportation of water from other locations

• desalination of saline water (ground and underground)

source:Ahmed M. Hamed et al, 2009.

“Rain water harvesting is the

technique of collection and

storage of rain water at

surface or in sub-surface

aquifers, before it is lost as

surface run-off”

Types of rainwater harvesting

1.Surface runoff harvesting2.Roof top rainwater harvesting( RRWH)

• Design considerations such as optimum tank size, efficiency of RRWH system.

• Filtration of rainwater• Economic considerations• Social challenges• Effect of climate change • Water quality related

issues

Challenges $ scope of RRWH in India

Source: IMD,2010.

Importance of water qualityAccording to WHO(2013), 80% of diseases are caused due to contaminated water.

Every 21 seconds, another child dies from a water-related illness”(world water assessment programme)

In a DRWH system, which consists of a collection system (root), a conveyance system (gutters or pipes) and a storage system (tank or cistern), contamination of water can occur at any of these states

Precipitation event

Catchment area

Conveyance system

Storage tank

Rain water quality criteria based on WHO(potable

water)parametersE- Coli 10 cfu/100 mLAmmonia <1.5 mg/LChlorine <5 mg/LAluminum Not relevantpH 6.5 – 8.5Turbidity Not relevantNitrate/ nitrite Not relavent

Source: WHO, 2004.

Factors Affecting DRWH Water Quality

1. pollutant concentration in the rain;

. source:A singh et al, 2012,Lucknow.

• Objective : effect of air pollution on rainwater quality• Rain water samples collected from different parts of

lucknow• Physicochemical properties are evaluated• results:• Intial rain-pH(4.6), chloride(17.04mg/L), CO2(9.2 mg/L)• Further values reduced to pH(6.24), chlorde(5.98mg/L),

CO2(2.2mg/L)

source:A singh et al, 2012,Lucknow.

2.Type of roof material and age of roof

• Type and age of roof• Samples taken from - Aged roof different roofing material(tile, - New roof asbestoses, fibre, aluminum,GI)• Samples collected in plastic tanks• 100 samples collected and evaluated different qualty

parameters

Sorce:Meera et al. 2011, kerala.

Comparison between aged roof and new roof

Source:Meera et al. 2011, kerala.

Comparison between different roofing material

• Turbidity( NTU) : asbsetose(2.70) and tarsheet(2.53) has more turbidity

• Conductivity(µs/cm) : More in case of GI sheet(2.34)• Zn (mg/L) : More in GI sheet (42) • All parameters more in case of aged roof than new

roof• Suitabilty for rain water harvetsing- tile> aluminium>GI

Source:Meera et al. 2011, kerala.

3. Area of roof, period of dry spell and rain fall

intensity• The purpose of this study was to examine the factors affecting the biological contamination of rain water

• Samples collection • 60 randomly selected residences 30(metal roof) (30 asbestoses)• Samples collected in 10 different rainy days• Total coliform bacteria and turbidity was evaluated

Source:Ifte Choudhury et al, 2008, Texas.

• Evaluate the data by hypothetical analysisResults: • Turbidity – directly proportional to the dry

spell period and roof area• Total coli form bacteria - Increase with

rainfall intensity

Source:Ifte Choudhury et al, 2008, Texas.

4. Impact of storage media

• Objective : impact of storage media on rainwater quality

• Sample collection - from 3 different storage media (metal tank,

plastic tank and concrete tank)• Physical, chemical and biological parameters

analyzed.

source:Achadu et al, 2013, nigeria.


• Physio chemical properties of rainwater is mainly effected by storage media.

• Microbiological quality is not effected by storage media.

• Metal tank and concrete tank shows great difference in properties

• The study suggest that concrete and plastic tank more suitable for rain water harvesting


5.Other factors…•Wind blown dirt•Leaves •Feacal droppings from birds and animals•Insects

Contamination of DRWH water

Microbiological contaminationmicroorganisms Disease Reference

E.Coli gastrointestinal illness Koplan et. al. 1978, west indies

Campylobacter campylobacteriosis Brodribb et. al. 1995, Austarlia.

Giardia Giardiasis Lester 1992, Australia.

salmonella salmonellosis Simmons and Smith, 1997, Newzland.

Place and reference

Samples collected from

Parameters tested findings

NewZealand(simmons et al. 2001)

Rain water tank(125 samples)

HPC, TC, FC, Aeromonas, Salmonella, Cryptosporidium

56% samples exceeds drinking water quality.Aeromonas in 16% samples.Salmonella in 1 sample.Cryptosporidium in 2 samples.

Thailand(Appan 1997)

Roof catchment (709 samples)

FC, FS 76% samples exceeds the Who standards.

Nigeria(ugha et al. 2005)

Roof catchment(76 samples)

HPC, PseudomonasShigella,vibrio, salmonella

High HPC an all samples.Pseudomonas in all samples except Zn Roof. High amount of salmonella in 36% of samples.

New delhi(Vasudevan et al. 2004)

Roof runoff ( 54 samples)

Giardia, Cryptosporidim

45% samples positive for Giardia.23% samples positive for Crypotosporidium.

Kerala( Sivanadan et al.2001)

Rain water tanks( 30 samples)

FC 93% samples contaminated with FC.FC> 500MPN/100mL in 30% samples.

Objective: “Determine the bacteriological and nutrient quality of rooftop harvested and stored rainwater for individual household use as well as for community use in rural and urban settings.”

Method1.Collection of sample- 9 storage tanks for individual household use - 8 storage tanks each for rural and urban community

use were selected• Physicochemical properties and biological analysis

was doneSource:Y. Jesmi et al, 2014, kerala.

Results

• Physio chemical quality• The pH of rainwaterranges from 4.5 to 6.5• DO levels of stored

rainwater in urban and rural areas were above 3 mg/L.

• Bacteriological analysis• FC and FS load relatively

lower• E. coli was isolated from

nearly 50% of samples for community use and 20% samples( house hold)

Source:Y. Jesmi et al, 2014, kerala.

Chemical contamination

• Chemical contamination results from

- Air pollution (industrial and traffic emissions)

- Runoff and leaching of chemical substances

- Toxic material use

John Gould

• Most places the elevated concentration of the lead is reported

• Lead levels exceeding 3.5 times WHO drinkingwater standards have also been noted (Yaziz et. al.

1989, Australia).• Sources of lead - lead flashing, leadheaded nails, lead

based paints/primers for roof construction• In few cases elevated level of magnesium , zinc and

iron is reported.

Vineyard et al.

Physical contamination• Physical contamination includes- Inorganic and organic sediments

like sand, silt, clay, or plant material.

• Physical contamination affects the colour, odour or taste of the water, but it poses no direct health risk.

• significant health risk is the breeding of mosquitoes in or near RWH systems .

• Mosquitoes can breed in a storage tank, in blocked rainwater collection gutters, drains and pools around a storage system, due to inappropriate operation of the RWH system or poor construction.

Treatment methods

First flush system

• First flush devices - effectively operated and maintained,

first flush systems can significantly improve the quality of roof runoff

- “ for each mm of first flush the contaminate load will half” ( sartor and boyd, 1972)

- The capacity of first flush system designed according to the roof area

Filtration: • Several types of filter

elements • a piece of cloth • Mesh• Sand bed• Charcoal• Efficiency -mesh filter

Hussain et al.

• Chemical Disinfection: Chemicals used include

• Chlorine and chlorine compounds

• Iodine doses in suitable form

• Ozone• Potassium permanganate

(oxidant)• Hydrogen peroxide

(oxidant)

• Physical Disinfection• Boiling• UV irradiation

Source:RGNDWM, 2010.

Recommendations

• Technical• All rain water tanks should be fitted with filter and first flush

system.• More aware on Operation and Maintenance of the tanks• Corroded GI roof can be source of metal contamination (Zn) of

rain water, therefore care should be taken to replace corroded GI sheets.

• Rain water tank should be securely covered for protection as well as to prevent dust and runoff as well as insects getting into the tank.

Financial and Other implications• Introduce a loan scheme or a subsidiary to households to bear the

initial cost of constructing a tank.

Source:Tanuja Ariyananda , 2009, srilanka.

CASE STUDY 1

Rain Water Harvesting: Effect of Age of Roof on Water Quality

Eletta O.A.A. and Oyeyipo J.O.Department of Chemistry, University of Ilorin, Nigeria,2008.

• Objective: Determination of trace elements in harvested rain water samples and the effect of age of roof sheet on rain water quality

• Method :Samples is collected for a duration of 8 months.

• Three sets samples collected from direct rain, new roof , aged roof

• Heavy metal analysis _Atomic Absorption Spectrophotometer model 210 VGP.

Source:Eletta et al, 2008,nigeria.

FePb

ZnCu

0

2

4

6

8

10

12

14

16

WHO

EPA

canadian

Direct

New Roof

Aged Roof

WHO EPA

canadian Direct

New Roof Aged Roof

results


resultsMetals

WHO EPA Canadian Direct New roof

Aged roof

Fe 0.30 0.10 0.30 0.09-1.05

1.02-3.01

2.36-4.50

Pb 0.05 - - Nil Nil-0.01 Nil-0.03

Zn 5.00 5.0-15.0 5.0-15.0 0.12-0.36

2.03-3.43

2.39-3.96

Cu 1.00 0.05-1.50

0.05-1.50 Nil-0.13

0.02-0.10

0.11-0.33


• Conclusion• pH ranges from 6.7 to 7.2• Pb not detected• Cu is very low• Zn is higher in roof harvested samples than direct

rain fall but within the limit.• Fe shows higher elevation in aged roof.• This results shows the effect of eroded material in

the DRWH water quality


Case study 2

“Improvement in the purification of roof water harvesting system”

ByBlessy V A and Munna P V

KELAPPAJI COLLEGE OF AGRL ENGG & TECHNOLOGY KERALA, 2015.

• Objective: -To develop the micro mesh filter for better filtration

efficiency -To develop a first flush system suitable for upward flow

micro mesh filter • Method:• Samples collected from different type of roof

(asbestoses, Tile and concrete)• Dimension of the designed filter-Height of the filter element was 300 mm and the mesh

area was 0.047m²-Capcity of first flush sytem – 18 l

• Analyzed water pH, EC, turbidity, TSS, TDS and filtration efficiency from inflow, outflow water

• Result:• pH of the samples ranges from 6.8 to 7.9• EC ranges from 0.05 to 0.09 dS/m. • TDS ranges from 0.03 to 0.05ppm more in case

of tile roof• First flush system along with the 60 micron

filter shows that there is higher reduction of TDS value.

conclusion• Untreated roof runoff has been widely used

for drinking purposes for many parts of world.• very few reports of serious health problems. • Recent findings suggest there is little room for

complacency and every effort needs to be taken to minimize rainwater contamination.

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THANKS......

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domestic rain water harvested water quality : an overview

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