Thames Water still using dowsing rods to detect leaks despite evidence they don’t work

Thames Water engineers working on a leak in Holloway, north London. (PA)
Thames Water engineers working on a leak in Holloway, north London. (PA)

Thames Water is still using the ancient dowsing method to hunt for leaks, despite scientists saying it doesn’t work.

The company, which services nearly 15million homes, has admitted some of their engineers continue to use dowsing rods in their jobs.

The method, which dates back to the 16th century, involves someone seeking water holding two L-shaped or one Y-shaped rod in front of them, which is then said to twitch or cross if there is water underground.

Most water companies were still using dowsing until 2017 when it was dropped after scientists concluded it did not work.

Water reglator Ofwat has advised water firms to stop wasting money on the method which has been dismissed by experts as no better than guesswork.

Ten of the UK’s 12 water companies confirmed their engineers used the method in 2017, compared to just two in 2023.

Thames Water, which loses millions of litres of water in leaks every day, confirmed that their engineers can carry dowsing rods, with one of its workers telling New Scientist they are used to verify or ‘narrow down’ results.

Lloyd Butter told the publication: “Some people they work for, some people they don’t. If they work for you, you come to trust it.

“People are sceptical of it, and I was sceptical when I first saw it. I started using them because I saw someone else use them and I have found leaks.”

Dowsing has been branded ‘witchcraft’.

A Thames Water spokesperson said: “Finding and fixing leaks is our top priority, and we use a range of tools to do this. We’re using innovative AI technology which enable us to detect and fix leaks before they become visible, along with traditional tools.“The onboarding tool box we provide to engineers contains a wide range of kit including: correlators; ground microphones; valve keys; and listening sticks. We don’t provide dowsing rods as standard issue, however some engineers may choose to use their own to help to narrow down results from other leak detecting equipment in particularly rural areas.“We also have an extensive capital programme to help us fix more leaks in the future. In the next 3 years we will spend over £55m installing dynamic pressure management helping to modulate pressure across our network for varying demands, helping reduce leakage. And in the next 3 years we will spend close to £200m on replacing water mains.“We’re determined to drastically reduce the amount of water that escapes from our pipe network to help protect customer supplies for now and future generations. We are repairing over 1,100 leaks per week, whether they are visible or hidden below ground.”

Severn Trent, which supplies homes across the Midlands and Wales, said that while some of its engineers might have dowsing rods with them, it is not company policy to use them.

The firm claims to use satellite and drone technology, as well as acoustic listening devices to find leaks before they become an issue.

A spokesperson for Severn Trent said: “We do not consider dowsing rods to be an effective way of finding leaks and as such we don’t issue them to engineers.

“Instead, we invest in electronic mapping systems and an array of cutting-edge technologies to react quickly when bursts happen.

“Our teams are constantly monitoring the network, checking for flow rate and pressure that may indicate leaks.

“Their expertise, combined with the technology we use, means we manage to detect 60% of leaks before they become an issue for the public.”