Household Water Use and Health Survey for the Water Safety Plan Linden, Guyana December 2007 U.S. Centers for Disease Control and Prevention (CDC) Suggested citation: Centers for Disease Control and Prevention. 2007. Household Water Use and Health Survey for the Water Safety Plan, Linden, Guyana. Atlanta: U. S. Department of Health and Human Services. The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the Centers for Disease Control and Prevention. Use of trade names is for identification only and does not imply endorsement by the Centers for Disease Control and Prevention, the Public Health Service, or the U.S. Department of Health and Human Services.
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Household Water Use and Health Survey for the Water Safety Plan
Linden, Guyana
December 2007
U.S. Centers for Disease Control and Prevention (CDC)
Suggested citation: Centers for Disease Control and Prevention. 2007. Household Water Use and Health Survey for the Water Safety Plan, Linden,
Guyana. Atlanta: U. S. Department of Health and Human Services.
The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the Centers for Disease Control and
Prevention.
Use of trade names is for identification only and does not imply endorsement by the Centers for Disease Control and Prevention, the Public
Health Service, or the U.S. Department of Health and Human Services.
Household Water Use and Health Survey for the Water Safety Plan Linden, Guyana, December 2007 U.S. Department of Health and Human Services Centers for Disease Control and Prevention National Center for Environmental Health Agency for Toxic Substances and Disease Registry Division of Emergency and Environmental Health Services Use of firm, trade, and brand names is for identification only and does not constitute endorsement by the U.S. Government. Additional information can be obtained from Dr. Richard Gelting, PhD Environmental Engineer CDC/NCEH/DEEH/EHSB 4770 Buford HWY, NE Mail stop: F-28 Atlanta, GA 30341 USA Telephone: 770.488.7067 Fax: 770.488.7310 E-mail: [email protected]
Demographics ............................................................................................................... 10 Water sources and service............................................................................................. 11 Water storage ................................................................................................................ 13 Household water treatment ........................................................................................... 14 Water costs.................................................................................................................... 14 Consumer perceptions and satisfaction......................................................................... 15 Sanitation ...................................................................................................................... 15 Diarrhea and Other Illnesses......................................................................................... 16 Community Concerns ................................................................................................... 18 Free chlorine residual testing of tap and stored water .................................................. 18 Microbiological testing of tap and stored water ........................................................... 21
Water quality................................................................................................................. 23 Water treatment............................................................................................................. 25 Water storage ................................................................................................................ 26 Water costs.................................................................................................................... 27 Perceptions of water quality.......................................................................................... 28 Diarrhea and other illnesses .......................................................................................... 29 Other community concerns ........................................................................................... 31
LIMITATIONS............................................................................................................... 31 CONCLUSIONS AND RECOMMENDATIONS........................................................ 33
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TABLES Table 1: Communities surveyed and estimated population size................................. 37 Table 2: survey population characteristics by water treatment plant service area.. 38 Table 3: Consistency of water service by water treatment plant service area .......... 39 Table 4: Potential risk factors for diarrhea and diarrhea prevalence in previous 2 weeks among children under five years of age............................................................. 40 Table 5: Water quality data in different household samples and at treatment plants........................................................................................................................................... 41 Table 6: Microbiological test results (total coliforms and E. coli) for direct-from-tap, drinking-water container (DWC) and tank samples ................................................... 42 FIGURES Figure 1: Linden Household Survey Water Treatment Plan (WTP) Service Area Distribution Map............................................................................................................. 43
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BACKGROUND
The Water Safety Plan (WSP) aims to identify hazards to drinking water quality that can
be introduced at multiple points from “catchment to consumer.” It does not, however,
traditionally provide for identifying hazards that could compromise drinking water
quality after it reaches the household, such as contamination associated with water
collection, storage and treatment practices within the home. This Household Water Use
and Health Survey was therefore conducted as part of the Water Safety Plan for Linden,
Guyana in order to understand the fate of water from the time it reaches the home to the
point of consumption.
The survey, consisting of a household questionnaire and testing of household water
samples, looked at issues such as consistency of water delivery, quality of delivered and
stored water, community perceptions, and consumer practices concerning water use that
impact customer satisfaction and the safety of drinking water within the home. This
survey is intended to provide information about customer experience and concerns for the
WSP team to consider as they go through the process of system and management
evaluation and implementation of changes resulting from the Water Safety Plan.
Five water treatment plants serve the residents of Linden, and each treatment plant serves
its own distribution area. Despite some connections between distribution areas, the
system is operated (through valve adjustments) such that each area is effectively an
independent distribution system. This survey, therefore, is an evaluation of five separate
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water treatment plant service areas, under the management of Guyana Water Incorporated
(GWI), the national water utility of Guyana.
CDC provided technical assistance for survey planning and implementation in
collaboration with Guyana Water Incorporated and the Linden Health Department.
OBJECTIVES
Specific aims of the household survey were:
1. to determine the quality of household water at the point of collection and at the
point of consumption to determine the quality of water reaching consumers and if
deterioration of water quality occurs due to storage and handling practices;
2. to describe water use and treatment practices at the household level, user
satisfaction, and perceptions of water quality by consumers;
3. to estimate the prevalence of diarrheal illness in the population, evaluate its
possible association with water-related variables, and describe health-seeking
behaviors;
4. to determine the quality and consistency of water service provision, identify
issues of special concern, and evaluate the impact that interruptions in service or
pressure or other service-related issues may have on the safety of water
consumed.
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METHODS
Sample selection The survey was conducted in communities served by the five water treatment facilities
operated by Guyana Water Incorporated (GWI) in Linden, Guyana: Amelia’s Ward,
Linden Power Company (LPC), McKenzie, West Watooka, and Wisroc. Additional
households from newly developed areas and informal (squatter) settlements that were not
connected to GWI’s distribution network were also sought for inclusion to allow for
comparisons between households on and off of the piped water delivery system. (Table 1,
Figure 1)
Because the survey was descriptive and not based on a single outcome variable, the total
sample size was determined based upon achieving a 95% confidence interval, ± 5%
around the most conservative estimate of several outcome measures of potential interest,
including self-reported two-week diarrhea recall, the presence of residual free chlorine in
tap water, and household treatment of water. It was determined that a sample size of
approximately 500 would provide the desired level of confidence. The sample size of
households not connected to the GWI piped water system was not large enough to permit
statistical analysis with households on the distribution network; such comparisons are
only to identify potential trends between these different areas.
Maps indicating the service areas for each community were provided by GWI and the
Guyana Bureau of Statistics. Population estimates were based on the 2001 census, current
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GWI service connection records, and estimates of community informants in newer
settlements or where there was no GWI service.
Selection of houses within the community was based on stratified systematic sampling.
The number of households visited in each community was allocated proportional to the
size of the community. The total number of households was divided by the sample size to
produce a sampling interval. The surveyors were assigned a random number between one
and the sampling interval and counted off this number from one corner of the community
to determine the house for the first interview. The surveyor then systematically walked
through the community selecting every nth household for inclusion in the survey. If no
adult was home at a selected household, the surveyor would return later that same day. If
no adult was available upon return, or if the house was abandoned or unoccupied, the
next closest house was selected.
Ten local interviewers were employed to conduct the survey. A three-day training was
provided to review the questionnaire, household selection, interview techniques and
water sample collection and testing. The questionnaire and survey methods were pilot
tested in the field. A designated field coordinator managed the daily activities of field
personnel. Community sensitization, using local television announcements to inform
people of the survey, was done in order to increase participation and for the sake of
interviewer safety.
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Household Visits At each selected household, a questionnaire was administered and water samples were
tested for free chlorine. For a subset of the selected households, water samples were also
collected for microbiological testing.
The household questionnaire aimed to gather information about demographics, sources of
water, consistency of service throughout the day and year, possession of a household
storage tank, storage and treatment practices within the home, handwashing practices,
sanitation, incidence of diarrhea and other illnesses, and health-seeking behaviors.
Several questions were aimed toward understanding perceptions of community members
concerning water quality and safety and other community and health concerns.
Water Testing Water samples from each household were tested on site for free residual chlorine using
Hill, most of Canvas City, Christianburg (sections B and C), Half Mile, Silver City, Silver Town, Watooka Hill, West Watooka,
8,400 142
Wismar Housing Scheme, parts of One Mile and Victory Valley
Wisroc Block 22, Blueberry Hill, D'Anjou Park, Ho a Shoo, Micah Square, Wisroc, some of Canvas City, part of Victory Valley, most of One Mile/Extension
8,175 138
None 3rd Phase/ Phase 1B, Amelia’s Ward New Housing Scheme, Blueberry Hill squatter area, Old England, West Watooka squatter area, Siberian
135 25
Linden Total 29,515 535
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Table 2: survey population characteristics by water treatment plant service area
# of HHs Have an in- Have a water Have a flush Believe their # of Paid Three
Table 4: Potential risk factors for diarrhea and diarrhea prevalence in previous 2 weeks among children under five years of age Variable Frequency with
diarrhea (%)
Odds Ratio*
Confidence Limit (p-value)*
Hrs/day without water (range 0-22) 1.01 0.93-1.09 (0.87)
Handwashing with soap (respondent) Always/almost always Sometimes
17 (13.1) 15(13.0)
†
†
Never/almost never 0
Free Cl2 residual at tap ≥0.2 mg/L <0.2 mg/L
2 (12.5) 22 (13.8)
1.12 ref
0.12-10.215 (0.92)
Free Cl2 residual in tank <0.2 mg/L ≥0.2 mg/L
3 (60.0) 0 (0.0)
†
†
Free Cl2 residual in drinking water containers 20 (11.8) 0.35 <0.2 mg/L 5 (27.8) ref 0.09-1.33 (0.12) ≥0.2 mg/L *Logistic regression model adjusted for effect of clustering by WTP service area and household †Unable to calculate due to zero values ref = referent group for calculating odds ratio
Table 5: Water quality data in different household samples and at treatment plants
*includes one sample with >3.5 mg/L free Cl2 residual
WTP service area
Free Cl2 at tap <0.2 mg/L
Free Cl2 at tap ≥0.2 mg/L
Mean of free Cl2-positive tap samples (mg/L)§
Free Cl2 in tank <0.2 mg/L
Free Cl2 in tanks ≥0.2 mg/L
Mean free Cl2-positive samples in tank (mg/L)§
Free Cl2 in DWC <0.2 mg/L
Free Cl2 in DWC ≥0.2 mg/L
Mean free Cl2-positive DWC samples (mg/L)§
Mean free Cl2 leaving plant on survey days†
(mg/L)
Mean pH leaving plant on survey days†
Mean turbidity leaving plant on survey days†
(NTU)Amelia’s Ward
19 (86%)
3 (14%)
0.28 35
(90%) 4
(10%) 0.64
54 (91.5%)
5 (8.5%)
0.69 0.56 6.3 -
Linden Power Company (LPC)
55 (93%)
4* (7%)
0.40§ 22
(96%) 1
(4%) 0.30
43 (91.5%)
4* (8.5%)
1.60§ 0.79 5.4 3.7
(range: 0, 7)
McKenzie
47 (92%)
4 (8%)
0.27 17
(94%) 1
(6%) 0.30
55 (98.2%)
1 (1.8%)
0.50 1.21 4.9 8.3
(range: 5, 12)
West Watooka
100 (99%)
1 (1%)
0.20 19
(95%) 1
(5%) 0.30
92 (92.9%)
7** (7.1%)
1.68§ 1.20 5.0 9.4
(range: 5, 15)
Wisroc
72 (90%)
8 (10%)
0.26 29
(94 %) 2*
(6%) 0.30§
87 (83.7%)
17** (16.3%)
1.01§ 0.51 6.4 3.1
(range: 0, 5)
None na na na
3 (75%)
1 (25%)
0.20 19
(90.5%) 2*
(9.5%) 0.20§ na na na
Total Linden
293 (94%)
20 (6%)
0.29 125
(93%) 10
(7%) 0.43
350 (90.7%)
36 (9.3%)
1.27 0.85 5.6 6.1
** includes two samples with >3.5 mg/L free Cl2 residual § Excluding samples that surpassed the upper limit of the test method (>3.5 mg/L) †Reported daily by plant operators on 7 survey days
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Table 6: Microbiological test results (total coliforms and E. coli) for direct-from-tap, drinking-water container (DWC) and tank samples Source of water sample