A low-cost home water filter

This paper reports the performance of a low-cost home water filter, with iron hydroxide-coated sand as medium, in removing turbidity, bacteria and viruses from water. Performance of the water filter was evaluated in long-duration laboratory tests employing a sewage-spiked canal water (turbidity 20-50 NTU; heterotrophic bacteria 800-4700 CFU/mL; faecal coliforms 60-400 MPN/100 mL) and a poliovirus-spiked canal water (turbidity 28-52 NTU; faecal coliforms 4-93 MPN/100 mL; poliovirus 90-190 MPNCU/mL), mimicking home treatment of water. A substantial improvement in aesthetic and microbiological quality of the waters was effected. Effluent (filtered water) characteristics were: turbidity 2-3 NTU, heterotrophic bacteria < 500 CFU/mL, faecal coliforms 3-4 MPN/100 mL, and poliovirus 8-19 MPNCU/mL. Silver-incorporated medium produced only a marginally superior effluent in terms of heterotrophic bacteria and faecal coliforms, even though silver incorporation effected substantial inactivation of bacteria on the medium. A procedure is suggested for renewing/replenishing the medium when it loses its effectiveness. Because of its low cost (material and fabrication cost: Rs. 200 and cost of medium: Rs. 80; 1 pound = Rs. 70) and simple operation, the water filter appears promising for use in rural areas of developing countries. The water filter should be subjected to field testing to assess long-term effects on performance.