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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 Use. Katherine Westphal MPH Candidate, 2008. EARL WALL, m.S., Kellogg Schwab, PhD., M.S. Ceramic Water Filter (CWF). Technology developed in Guatemala in 1981

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Katherine Westphal MPH Candidate, 2008

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  1. The Effectiveness and Sustainability of a Low-cost Water Filter in Removing Pathogens during Long-term Household Use Katherine Westphal MPH Candidate, 2008 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 98-100% 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: • Laboratory – • tested bacteria, virus and protozoa removal of 24 CWFs from Honduras • Field survey - • a cross-sectional survey of households in Nicaragua that received a CWF • Field assessment – • 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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