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KATHERINE WESTPHAL MPH CANDIDATE, 2008 The Effectiveness and Sustainability of a Low-cost Water Filter in Removing Pathogens during Long-term Household.

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Presentation on theme: "KATHERINE WESTPHAL MPH CANDIDATE, 2008 The Effectiveness and Sustainability of a Low-cost Water Filter in Removing Pathogens during Long-term Household."— Presentation transcript:

1 KATHERINE WESTPHAL MPH CANDIDATE, 2008 The Effectiveness and Sustainability of a Low-cost Water Filter in Removing Pathogens during Long-term Household Use EARL WALL, M.S., KELLOGG SCHWAB, PHD., M.S.

2 Ceramic Water Filter (CWF) Technology developed in Guatemala in 1981 Potters for Peace promotes CWF Filters are produced by local organizations Manufactured in 23 factories throughout 20 countries Worldwide over 300,000 sold Organizations promoting CWF include Save the Children, UNICEF and Oxfam

3 CWF production Made from locally available clay, screened combustible material (sawdust or rice husks) and water Pressed into bucket shape with a hydraulic press Fired for 8-12 hours in Mani Kiln Filtration flow rate (1-2.5 Ltr/hr) Painted with colloidal silver Sold with plastic receptacle and spigot for $15 (small) and $20 (large)

4 Background Research to date - Non-peer reviewed studies have found: CWF removes between % bacteria effective in removing protozoa although the virus removal is minimal Concerns – Effectiveness of the filter to remove water-borne pathogens Possible quality control issues within and between manufacturing facilities

5 Research objectives Quantify the effectiveness of the CWF to remove water-borne pathogens in the laboratory and in the field Evaluate the long-term sustainability of the CWF Determine if the CWF should be promoted by organizations as a POU water treatment system

6 Study design 3 Parts: 1. Laboratory – o tested bacteria, virus and protozoa removal of 24 CWFs from Honduras 2. Field survey - o a cross-sectional survey of households in Nicaragua that received a CWF 3. Field assessment – o in-situ tests of CWF effectiveness to remove bacteria

7 Research findings Laboratory (15 CWFs with silver) – Field – 53% (23/43) of filters removed 100% of E. coli 78% (34/43) of filters removed > 95% E. coli 9.3% (4/43) of households had more E. coli in filtered water than pre-filtered water

8 Research findings Cross-sectional survey (167 households) – 48.5% of households had stopped using filter daily Among households not using the CWF, the primary reasons were : broken spigot ( 58.0%) broken ceramic filter (40.7%) broken receptacle (30.9%) Even among households using the CWF, 31.4% had a broken spigot Only 26.3% of households knew where to purchase CWF spare parts 86% of households reported that the CWF provided enough water for their family to drink All households surveyed liked the taste of the filtered water The majority of households reported that they liked the CWF because it cleaned the water and kept their family healthy

9 Sustainability Social/Cultural People like the taste of the filtered water and appearance of the filter Households consider the CWF beneficial enough to pay for it Economic Provides employment for local potters A one-time cost if unit does not break Technical Effectiveness – Significantly reduces bacteria and protozoa in water Does not effectively remove viruses and there is no residual protection Durability – The ceramic filter, spigot and receptacle are fragile and break easily Spare parts are not readily available Environmental Uses locally available materials and fuel efficient kilns for firing filters

10 Conclusions Laboratory - CWF improves the quality of water but it does not consistently remove water-borne pathogens to meet USEPA standards Field - In general, the CWF improves household water quality Without modifications to the spigot and receptacle, long-term sustainability will not be achieved Overall - Necessary to consider the social, economic and environmental constraints of a country before defining water quality standards

11 Recommendations CWF - Adaptations to the spigot and/or receptacle of the CWF Increase availability of CWF replacement parts Research - Compare effectiveness of filters across production sites Longitudinal study of diarrheal prevalence comparing households with a CWF to those without Quality assurance - Establish QA protocols for CWF production Develop a certification process for locally-produced CWFs

12 Acknowledgements The Johns Hopkins Center for a Livable Future Ron Rivera, Potters for Peace Save the Children Canada, Nicaragua Earl Wall, Kellogg Schwab, Kristen Gibson, Stephanie Guo, Casey Branchini and Jimmy Schissler Joan Kub and Sara Groves


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