The annual reports by the UK’s drinking water watchdog shows water supplies in England and Wales are among the best in the world – with 99.97% and 99.98%, respectively, of samples collected and tested meeting the required standards.

However, the document also reveals more than 36% of water quality failures in homes in England, and 51% of failures in homes in Wales, stem from plumbing issues in customers’ own properties.

Poor plumbing practices and fittings are one of the main causes of drinking water quality being affected, after it has been transferred safely from water mains into people’s homes.

Now WaterSafe, the UK register for approved contractors working with drinking water, is urging homeowners and property managers to always employ someone who is officially approved to work on their plumbing system – to help keep their drinking water safe and wholesome.

Plumbers and other specialist water services contractors on the WaterSafe database have specific training in the Water Supply (Fittings) Regulations, which are designed to protect water supplies from the risk of contamination.

Julie Spinks, Director of WaterSafe, said: “The Drinking Water Inspectorate’s latest annual reports for England and Wales tell us our water supplies are world class and we want to play our part in making sure drinking water is as healthy when it comes out of customers’ taps, as it is when it leaves your local water company’s mains and pipes.

“There are a number of things which can affect water quality in homes, or other buildings, such as incorrectly connected appliances likes dishwashers and washing machines, misconnections to waste pipes, poor quality taps and fittings and even contamination from home oil storage tanks.”

Ms Spinks added: “Only plumbers and other specialist contractors with the right skills and knowledge to work safely with drinking water are allowed to join the WaterSafe register. This gives customers reassurance that they are using a competent and qualified professional to work on one of the most important supplies to their home.”

Each year thousands of samples of water are taken from reservoirs, water treatment works, pumping stations, water mains and customers’ taps by water companies.

These are tested in laboratories to monitor water quality across a wide range of measures, in line with standards set by the World Health Organisation (WHO).

The results are published each year by the government’s watchdog, the Drinking Water Inspectorate (DWI). Marcus Rink, Chief Inspector at the Drinking Water Inspectorate, commented:

“Overall, drinking water in England and Wales is of an excellent quality and this is demonstrated through a continuing high standard of compliance with the required measures. People should, therefore, have confidence in their water supply.

“It’s important that whoever carries out plumbing work in your home ensures your drinking water remains clean and safe to drink. Therefore, we recommend you select an installer who is approved through a national accreditation body for competent and qualified installers, such as WaterSafe.”

Customers can find their nearest WaterSafe-approved plumber, or other specialist contractor, by visiting watersafe.org.uk, choosing the service they need and entering their postcode.