Outbreak of gastroenteritis associated with contamination of a private borehole water supply.

An outbreak of gastroenteritis affected 58 of 700 people served by a private water supply at a biological research institute located in a village. No cases were detected in 250 residents of the same village served by a public water supply over the same period. Consumer complaints of tainting and laboratory evidence of bacterial and chemical contamination were obtained for the private water supply, but not for the public water supply. The outbreak was probably caused by contamination from a nearby sewer of a borehole used for the private supply. The outbreak showed how a large, private water supply posed a substantial risk to public health. The regulatory framework for such water supplies should be modified to ensure their safer design and operation.