Private Water Supplies More Likely to Fail Water Quality Tests

Private water supplies in England are more likely to fail stringent water quality tests than public supplies, warns the UK plumber approval body WaterSafe.

WaterSafe is highlighting the risk as figures from the Drinking Water Inspectorate show 3.4 per cent of tests on privately owned and operated water networks failed to meet drinking water quality standards in the latest published results.

This is 80 times the rate of failures in public water supplies from the licensed water companies in England, which continue to be among the safest in the world.

Local authorities are responsible for regulating private water supplies – carrying out risk assessments and monitoring them. Each year the Drinking Water Inspectorate, which regulates public supplies, publishes a report on private supplies based on the local authorities’ findings.

These findings have prompted WaterSafe and the Drinking Water Inspectorate to urge private water supply owners and operators not to take any chances when it comes to protecting their networks – and customers – from potential contamination.

About two-thirds of private water supplies in England are used to supply a single domestic dwelling. The remaining private water supplies are used for the tourism and leisure sector (hotels, B&Bs, campsites and hostels) (66%), food premises (20%) and public buildings, such as schools, hospitals and care homes (13%).

The failures were mainly as a result of the water source not being protected from contamination, such as animal waste, insufficient treatment of the water or issues with the plumbing systems.

In one instance, a water company stepped in to issue a ‘Do Not Drink’ notice to a college after brown water was supplied for several days after an untreated private water supply which was being used to irrigate crops was illegally cross connected to the college’s drinking water supply.

Julie Spinks, Director of WaterSafe, said: “There are more than 37,700 private water supplies in England which supply drinking water to nearly 80,000 customers across households and businesses, but this report shows a worrying proportion of the samples taken have been deemed unsafe.

“Our message to those who own and operate these networks and sources of water is very clear – always be sure to employ a qualified plumber, such as WaterSafe approved as they are properly trained and competent in the water regulations which govern public water supplies. It makes sense to apply these same standards to private supplies to keep them equally healthy and avoid the risk of contamination right up to the tap.”

Marcus Rink, The Chief Inspector of Drinking Water for England, said: “These failures present a high risk to consumers and a potential danger to human health.

While there have been some improvements since we started reporting compliance figures for private water supplies, the failure rate is much worse when compared to public water supplies.
“This becomes even more concerning when you consider there are private supplies serving hospitals and schools, where there is clearly potentially greater risk of harm to more vulnerable consumers from poor quality tap water.

“We support WaterSafe, as its register of approved plumbers is there to help those responsible for protecting public health make an informed choice, and not least ensure any work is done safely by a skilled and competent plumber using approved materials.”

In 2019, there were 495 private water supplies in England (of which 78% were to commercial or public premises) deemed of potential risk to human health.

As a result, the local authorities who are responsible for monitoring them required the owners to take immediate steps to protect the public.

The annual Drinking Water Quality Reports for public and private water supplies can be read at

To find your nearest WaterSafe approved plumber, simply enter your postcode in the postcode search at the right.

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