Scottish Water is warning people to be on the look out for bogus callers.
It wants customers to follow its “three Cs” procedure card, check and call.
A spokesperson said: “When householders receive a cold call from anyone claiming to be from Scottish Water they should not, under any circumstances, open the door without first checking the caller’s identification card or letter.
“This should be passed through the letter box for verification as it stops a bogus caller forcing their way in.”
Identity cards should include a photo of the employee and the Scottish Water customer helpline, 0845 601 8855, and the company is urging anyone worried about a caller to phone to ensure they are genuine.
Anne-Marie Dewar, regional communities manager, said: “Householders shouldn’t let anyone into their home until they are sure of their identity.”
Scottish Water usually contacts customers in advance if it needs access to their home.
There may be times when they have to cold call, but these are never to collect money or to check premises for leaks or shut off the mains.
