Customers have received calls from somebody claiming to work for Severn Trent Water.
The person claimed the water was going to be cut off the following morning for not paying their water bill.
Elaine Taylor, security and resilience lead at Severn Trent, said: “We often hear about people trying to access homes by saying they’re from 'the water board', but this kind of phone call is unusual and obviously worrying for our customers.
"We can’t stress how important it is for customers to check the identity of the person calling to make sure it is a genuine call.
"Our agents are more than happy to give their names on calls and which department they are from.
“And just to reassure our customers - we would never cut anyone’s water supply off – we’re not legally allowed to.
"And we’re always trying to help our customers who are struggling with their bills.
“We’re very aware that people can struggle to pay their bills for a whole range of different reasons, which is why we’re proud to provide support to people who need it the most.
"We’re absolutely committed to reaching out to those who need our help, and our dedicated team will always be on hand for advice and assistance.
"We’d encourage anyone who thinks they may benefit from our range of support schemes to get in touch with us and we’ll see if we can help.
“Customers should also be wary of people who turn up at their door, claiming to be from Severn Trent.
"We offer a doorstep password scheme where you can apply for a password in advance that any legitimate visitors from Severn Trent will have when they come to your home.
"Our phone lines are manned 24-hours a day, seven days a week, and our employees fully expect customers to check their identity, either with a card or a call."
For more information, go to stwater.co.uk/my-account/help-with-account/what-is-the-doorstep-password-scheme0/ or call 08457 500 500.