Point-of-Use Drinking Water Treatment in Rural Cambodia Using Ceramic Pot Filters: Independent Appraisal of Interventions from

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1 Point-of-Use Drinking Water Treatment in Rural Cambodia Using Ceramic Pot Filters: Independent Appraisal of Interventions from Joe Brown University of Alabama, New College Departments of Biological Sciences and Civil and Environmental Engineering Mark Sobsey University of North Carolina School of Public Health, Department of Environmental Sciences and Engineering 2008 International Symposium on Household Water Management

2 Ceramic Water Purifier (CWP) Potters for Peace design Uses gravity-driven porous ceramic microfiltration, with rice husk burnout material Food-grade plastics, local materials and manufacture Very effective against bacteria and protozoa, potentially effective against viruses

3 Questions Do the filters substantially improve the quality of water users drink? Do the filters contribute to measurable health gains in users versus non-users? How do these factors change over the useful life of the filter? How long are filters being used by households? What factors contribute to successful long-term use in the target population?

4 Overview Intended to independently assess CWP implementations in Cambodia by 2 NGOs over a 4 year period Ceramic filter intervention projects (2000+ households) by IDE and RDI, Three provinces, thirteen villages, several implementation strategies & evolving technology Assess continued use, microbiological effectiveness, and health impacts of CWPs Design: cross-sectional and longitudinal

5 Part 1: Uptake and use study Cross-sectional study of 506 households Filters in use for 0-44 months Whether using or not, why or why not, and factors associated with use or disuse Collected extensive data on water, sanitation, hygiene, SES, education, behavior, etc Applied logistic regression models to identify factors associated with continued use or disuse Results are odds ratios adjusted for time in use

6 Part 2: water quality and health Longitudinal study (following households over time) Identified and recruited 80 households that have and still use CWP filters (~40 each) and 80 matched nonfilter (reference or control) households in the same geographic unit, same water source, child <5 Follow households for 10 weeks Diarrheal disease (7 day recall) for each family member Extensive data on covariates: water use and handling practices, hygiene and sanitation, SES and water quality (multiple samples) Regression models used to determine relationships between filter use and health, filter use and household water quality, and water quality and health Results are adjusted longitudinal prevalence ratios for diarrheal disease

7 Water quality data Treated and untreated water from households with filters Stored water (and if applicable, stored boiled water) from control households Analyze for total coliforms, E. coli by the membrane filtration method in the laboratory Measure ph and turbidity Three sampling rounds for each household over 10 weeks

8 All households who received filters (n=2000+)

9 Households in the cross sectional study (n=506) All households who received filters (n=2000+)

10 Households in longitudinal study (n=55) others recruited Households in the cross sectional study (n=506) All households who received filters (n=2000+)

11 WATER QUALITY AND HEALTH STUDY GROUP UPTAKE STUDY GROUP ALL HOUSEHOLDS

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14 13 villages in 3 provinces

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17 Results: cross-sectional study About 2% of filters fall into disuse per month post implementation Two-thirds of disuse caused by breakage of filter hardware Use over time compares favorably with other technologies Factors associated with continued use are: Knowledge and practice of related water, sanitation, and hygiene safe behaviors Use of surface water sources Cash investment in the technology (any amount) Factors associated with disuse are: Use of deep well water Time since implementation

18 Falloff in use of filters over time Percentage in use at time of follow up (%) y = x r 2 = Time since implementation (months)

19 Falloff in use of filters over time Percentage in use at time of follow up (%) y = x r 2 = Time since implementation (months) Compares favorably with other studies; some interventions less than optimal & limited availability for replacements

20 Factors related to discontinued use Broken (element, tap, container) Filter has passed its recommended lifespan The filter is too slow or insufficient The water does not need to be filtered Gave the filter to a friend or relative Other Percentage of users reporting reason for disuse (%, n=328) FILTERS IN USE AN AVERAGE OF 24 MONTHS

21 Results: longitudinal study Filters reduced E. coli concentrations in treated water by a mean 95.1% Potential underestimate; filter effectiveness up to 99.99% Median of 2 E. coli/100ml post filtration Two-thirds of effluent water samples from filters were <10 E. coli/100ml (low risk) Similar to data for stored boiled water No discernable trend in microbiological effectiveness over time in use Filters associated with a mean 46% reduction in diarrheal disease in users versus non-users Positive but weak relationship between E. coli concentrations and diarrheal disease (expected) LPR: 0.54 (95% CI )

22 Factors associated with continued use of the CWP post implementation Sex of household head Kandal Province Kampong Chhnang Province Pursat Province Living on less than 1 USD per day (self-reported) Caregiver reports receiving health education Access to a latrine Soap present in house (demonstrated) Caregiver reports washing hands at critical points Safe household water storage* Household members observed dipping hands into stored water Use surface water as PDWS Use rain water as PDWS Use well water (any) as PDWS Use deep 10m well water as PDWS Use shallow well water as PDWS Time since implementation (6-month blocks) Household purchased filter (at any price) Odds ratios (OR) for associations with continued use, controlling for time since implementation; bars are 95% CIs

23 Log 10 reduction of measured parameters 5 Log10 reduction in CWPs (all samples) Total coliforms E. coli Turbidity LRV = log 10 (E.coli untreated /E.coli treated ).

24 Performance stratified by time in use 5 4 Log10 reduction of E. coli Time since implementation (months)

25 Diarrheal disease impact Mean diarrheal disease prevalence over 10 week study period a Adjusted longitudinal prevalence ratio (LPR) b Intervention Control 95% CI c Age d All ages <5 years 5-15 years 16 years Sex Male Female Province Kandal Kampong Chhnang Pursat a. Two sampling rounds, February-April 2006 (dry season). Figures represent the proportion of individuals reporting diarrhea in the previous 7 days. b. Adjusted for clustering of diarrheal disease within households and within individuals over time. c. 95% confidence interval. d. Age in years at the time of the first household visit.

26 Other key results from study 77% of households reported cleaning the filter with a krama or other cloth, an average of 2.3 times per week Potential recontamination User behavior affects technology effectiveness! Boiled water stored in the household was of roughly the same quality as CWP water Storage is key

27 Summary of principal findings CWP significantly improves quality of water users drink, and can do so consistently for a long period of time, provided it doesn t break and is being used properly Filters fell out of use at a rate of about 2% per month after implementation; constant rate across location, time, and implementer Recontamination is a real problem Use of the filter can reduce diarrheal prevalence by about half, making it among the most effective interventions available

28 Recommendations: increasing sustainability Parts and replacements must be available and accessible Demand exists & filters will break over time Users need to know about distribution points Prevention of recontamination through appropriately designed software is essential Synergy with related interventions and education Filters should be sold to users

29 Acknowledgements Project staff: Proum Sorya, A Sisah, Choun Bunnara, Lim Kimly, Michelle Molina, Oum Sopharo, Song Kimsrong, Uon Virak, Van Sokheng Royal Government of Cambodia, UNICEF, AusAID Hilda Winarta and Sophary Phan (UNICEF) Drs Mao Saray and Chea Samnang (MRD) Mickey Sampson (RDI), Mike Roberts (IDE) Jan Willem Rosenboom (WSP-World Bank) Douglas Wait (UNC) Other Wat/San sector participants in Cambodia

30 Questions?

31 Post project appraisals and HWTS Less frequently done than new interventions Not always appealing to donors to look back at past projects when the new thing is moving forward Can be sobering to implementers, especially when studies highlight potential shortcomings of technologies being promoted by the organization May be perceived as more expensive or challenging with respect to study design and logistics How are these studies done? A critical feedback loop for institutional learning We don t need to reinvent the wheel! Are vital to advancing the current knowledge and identifying challenges, successes, failures Essential to make HWTS options the best they can be for providing safe water worldwide