The company said all genuine employees carry identification and on the rare occasions the company visits customers’ properties, this identification should be verified by calling 0800 1387878.
While making the call, customers should close their door on the caller. Genuine callers will have no issue with waiting while their credentials are verified.
A spokesman for Yorkshire Water said: “These people are out there, looking to con anyone they can so that they can rob them of their valuables and money.
“The people who carry out such acts are quite simply despicable and we want to make sure that no one falls victim to their evil tactics.
“It’s very rare that we do ever visit customers properties in the first instance, so customers should always be wary if they receive someone on their doorstep claiming to be from the company.”