SummaryInterventions to improve water quality, particularly when deployed at the household level, are an effective means of preventing endemic diarrhoeal disease, a leading cause of mortality and morbidity. Following a national survey indicating widespread faecal contamination of drinking water in Indian cities, a point-of-use water treatment unit was developed, which combines filtration and disinfection, does not require power or water pressure and has an operating cost of Rs. 0.25 (US$0.0057) per litre.We assessed the microbiological performance of the unit in the laboratory over the full 1500 l design life of the unit's consumable components. Geometric mean reductions for the units were more than 6 logs (99.9999%) for bacteria, more than 7 logs (99.99999%) for viruses and more than 3 logs (99.9%) for the test surrogate for protozoan cysts. Geometric mean reductions exceeded levels established for microbial water purifiers. The product water was free of detectable chlorine. If these results are validated in field trials, the deployment of the unit on a wide scale among vulnerable populations may make an important contribution to public health efforts to control intractable waterborne diseases.

Diarrhoea and other diseases associated with unsafe drinking water are a leading cause of mortality and morbidity worldwide and in India. Household-based water treatment has been shown to be an effective means of reducing this disease burden. Numerous such devices are manufactured and sold all over the world. We tested the microbiological performance of a leading brand of each of three common types of water treatment devices designed for household use in India: a ceramic candle gravity filter, an iodine resin gravity filter and an iodine resin faucet mounted filter. The ceramic candle filter and the iodine resin faucet filter reduced bacteria by more than 4 logs. However, the reduction of the MS2 phage (surrogate for viruses) and 3 micron microspheres (surrogate for protozoan cysts) in these devices was lower than log 3.4 and log 2.6, respectively. There were also high levels of residual iodide (and in some cases, iodine) in treated water from the iodine-based devices. While household water treatment could play an important role in India, standards are necessary so that consumers can ensure that the devices they purchase and use in the home are effective and safe.