A REVIEW OF THE HEALTH RISKS ASSOCIATED WITH UNDER-SINK POINT-OF-USE DEVICES Final (Review) Report to the Department of the Environment, Drinking Water Inspectorate
Report No DWI0318

Dec 1994


The employment of point-of-use devices is well-established on the North American continent as a result of the specialised needs of small and isolated communities. In the USA and Canada, it is often not practical to provide a supply of conventional treated drinking water, and point-of-use treatment is an economically attractive option, particularly if raw water of good quality is available. However, a large body of experimental data from both the USA and Canada has shown that the employment of certain types of point-of-use device leads to raised numbers of heterotrophic bacteria in drinking water, as a result of the multiplication of these organisms within the device itself. Granular activated carbon (GAC) filters are considered to be particularly prone to this problem.

In the UK, where the fitness for consumption of drinking water is protected by statute, and isolated individual water supplies are the exception, the economic and public health arguments for the fitment of point-of-use devices are slender. On the other hand, the presence of raised levels of heterotrophic bacteria in filter effluents must be a cause for concern. Although it has not been possible to demonstrate that the strains found in drinking water are pathogenic to man, at least one epidemiological study claims to show that an increased incidence of gastrointestinal infection is associated with drinking water from point-of-use devices. On microbiological grounds, therefore, it may be justified to discourage the fitment of point-of-use devices.

Copies of this report may be available as an Acrobat pdf download under the 'Find Completed Research' heading on the DWI website.