Microbiological performance of common water treatment devices for household use in India.

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.