Water companies are using divining rods to find underground pipes despite there being no scientific evidence they work, an Oxford University scientist found.
Sally Le Page said her parents were surprised when a technician used two "bent tent pegs" to find a mains pipe.
She contacted all the UK's water companies, and a majority confirmed engineers still use the centuries-old technique.
However, a number said the equipment was not standard-issue equipment.
The process of using divining rods, also known as dowsing, has been in use for hundreds of years.
A dowser will typically hold the rods, usually shaped like the letter Y, while walking over land and being alert for any movement to find water.
Evolutionary biologist Ms Le Page, whose parents live in Stratford-upon-Avon, first contacted Severn Trent Water via Twitter.
It replied: "We've found that some of the older methods are just as effective than the new ones, but we do use drones as well, and now satellites."
Other companies which gave a similar response were:
- Anglian Water
- Thames Water
- Scottish Water
- Southern Water
- Welsh Water
- United Utilities
- Yorkshire Water
Ms Le Page said: "I can't state this enough: there is no scientifically rigorous, doubly blind evidence that divining rods work.
"Isn't it a bit silly that big companies are still using magic to do their jobs?"
In a statement issued later, Severn Trent said: "We don't issue divining rods but we believe some of our engineers use them."
All the companies emphasised they do not encourage the use of divining rods nor issue them to engineers, and said modern methods such as drones and listening devices were preferred.
Northern Ireland Water, Northumbrian Water, South West Water and Wessex Water said their engineers do not use them.