A Comparative Analysis of the Microorganism Removal Capabilities of Potters for Peace Ceramic Water Filters Manufactured in Different Countries

Over 850 million people do not have access to improved drinking water. In areas where piped water systems are not available, point-of-use ceramic water filters (CWFs) may provide safe drinking water to individual households. One internationally promoted treatment system is a pot-shaped CWF adopted by the Potters for Peace (PfP) organization. However, differences in manufacturing practices may result in variable microorganism removal. To assess microbial removal capabilities, PfP CWFs with and without colloidal silver coatings from Honduras (n=24) and Nicaragua (n=24) were analyzed in a laboratory setting. Both reagent grade laboratory water and stream water were used as influent matrixes. Microbial removal was assessed by spiking 6L of water per filter with 106/ml of E. coli and MS2 bacteriophage. The influent and effluent were analyzed for spiked microbes and removal efficiencies were determined. With reagent grade water, colloidal silver lined filters from Honduras and Nicaragua demonstrated bacterial removal averaging 4.35 and 3.43 logs, respectively, and viral removal averaging 0.60 and 0.42 logs, respectively. Using spiked stream water, bacterial removal averaged to 4.64 and 4.06 logs, respectively, and viral removal averaged to 1.29 and 0.56 logs, respectively. Non-silver filters had minimal microbial reduction. In conclusion, silver coated CWFs were able to remove substantial levels of bacteria, but were limited in their capacity to remove viruses. However, 1 of 15 Honduran and 15 of 24 Nicaraguan filters had inconsistent microbial removal in reagent waters potentially due to reduced manufacturing quality control, necessitating further investigation of production variability.