Private Water Supplies and VTEC

VTEC (verocytotoxigenic E. coli) a serious diarrhoeal disease that can cause severe bloody diarrhoea and abdominal cramps. Usually there is little or no fever, and patients recover within five to 10 days. However, some people, particularly children under five years of age and the elderly, are at risk of a complication called haemolytic uraemic syndrome (HUS), in which the red blood cells are destroyed and the kidneys fail. This happens in up to 10% of child cases. HUS is the principal cause of acute kidney failure in children, and the majority of cases of HUS are caused by E. coli O157. Full information on VTEC and its management can be found here.

VTEC can be spread in a number of ways: directly from person to person, through consumption of improperly cooked meat (especially minced beef), salad vegetables contaminated by animal or human waste or irrigated with contaminated water, exposure to contaminated recreational water and consumption of, or exposure to untreated contaminated drinking water. 

Untreated private water supplies are an important method of spread: VTEC patients are 3 or 4 times more likely to consume untreated well or other private water than people who do not develop VTEC.  Well water can become polluted without any noticeable change in taste or smell. This can also apply to small, unregulated supplies that serve low numbers of people (generally less than 50).

Wells vary in their construction. Deep wells are desirable, but even deep wells, if there is a karst limestone covering, can be susceptible to contamination. It is important to seek advice regarding the safety of the water in your well, particularly on the need for filtration.

If you use private well water and you are not sure of the quality of the water, it would be important to boil the water (and seek to have a microbiological analysis carried out) if you notice any change in odour, taste or colour of the water, especially following rainfall. While microbiological contamination may be present in well water without any change in odour, taste or colour, heavy rainfall that would lead to contamination to water is likely to produce a change in the appearance and/or smell of the water.

It is not generally advised that wells be disinfected sporadically. It is better to put in place continuous treatment (such as UV disinfection or chlorination) or replace the supply.

It is important to ensure that the well-head would be protected from entrance of surface run-off or small animals eg birds or rodents. This may be especially relevant during extreme weather eg flooding.


Last updated: 1 October 2013