The risks of poor plumbing to drinking water in Wales

Drinking water quality in Wales continues to be rated among the best in the world however on the rare occasions problems do occur, this is often due to poor plumbing inside buildings.

The annual drinking water quality report, published by the Drinking Water Inspectorate (DWI), shows the drinking water supplied by water companies to more than 3 million people in Wales is safe, reliable and meets stringent high standards.

However, it also shows that on the few occasions the test standards were not met, about a third of all issues, and two-thirds of microbiological failings, were related to plumbing inside homes and buildings.

In one incident, a dead squirrel in a hot water cistern was discovered to be the cause of a ‘foul’ taste and smell in a customer’s water supply. A ‘do not drink’ notice was issued until the issues with the cistern had been resolved.

Another incident involved a leisure centre, where a ‘strong chemical’ smell and illness was reported. A ‘do not drink’ notice was again made and water company inspectors discovered corrosion inhibitors introduced to a heating system had made their way into the drinking water through an illegal cross connection between the two water systems.

So, to keep drinking water top quality when it enters homes and buildings, the national register for approved plumbers WaterSafe and the DWI are raising awareness of the risks of using inadequately trained plumbers and non-compliant products.

Marcus Rink, chief inspector of the DWI, said: “We recommend employing a qualified plumber accredited with the national register WaterSafe to carry out any plumbing work and only using compliant products.  This will help protect the quality of drinking water after it reaches homes and buildings right up to the tap.”

Plumbers approved by WaterSafe are fully qualified in the water fittings regulations, have insurance and are promoted by water companies to keep drinking water safe in homes. Compliant products include those approved by WRAS Approvals, NSF or KIWA.

Julie Spinks, managing director of WaterSafe, said: “It’s reassuring that drinking water quality remains exceptionally high in Wales but it’s important we take responsible steps to keep it that way for everyone inside our homes, public buildings and businesses by only trusting our plumbing and choice of products to qualified, approved professionals.”

The Drinking Water Inspectorate (DWI) for England and Wales provides independent reassurance that public water supplies in England and Wales are safe and drinking water quality is acceptable to consumers. Its annual report for Wales in 2024 is published here.