Anglian Water is urging customers in Luton and Bedfordshire to make sure they are protected from bogus callers this winter.
The water company has issued the advice to help keep customers safe during the dark winter evenings now that the clocks have gone back.
The number of reported cases of criminal activity goes up during the darker winter evenings, with many cases of distraction burglaries caused by bogus callers.
Nicola Harvey, from Anglian Water, said: "Unfortunately, this time of year we hear of a lot more cases of people targeting vulnerable or elderly customers.
"All too often bogus callers will claim to be from the "water board" - even though this organisation hasn't existed for over 40 years.
"We want all of our customers to feel safe in their own home which is why it's important they know what to expect from a genuine Anglian Water employee who may knock on your door."
Nicola added: "All of our employees carry identification and will happily hand it to you while you check it.
"Calling our Freephone number at any time of day will put you through to a member of our team who will be able to describe the person to you and confirm they are a genuine employee.
"If in any doubt we urge customers to check with us and not be pressured into letting someone into their home."
Customers in any doubt should close the door and phone Anglian Water, for free, on 03457 145 145 or alert the police.