BOGUS water board officials stole hundreds of pounds in cash when they tricked their way into the home of a 90-year-old woman in Kirkheaton.
The three white men, in their late 20s and early 30s, knocked on the door of a house on Moorside Road at about 5.30pm on Friday.
The homeowner's 75-year-old friend answered the door and was told there was a leaking pipe.
She allowed the men into the house to check for a leak.
But while two were in the kitchen the other crept into the bedroom and stole cash from a handbag hidden in a wardrobe.
Police are now warning householders in the area to be vigilant.
Detective Constable Steve Shaw, of Huddersfield CID, said: "We tend to find with these people that if they have been successful in an area they come back.
"We would like to warn people to be careful and keep an eye out, especially if they have elderly neighbours.
"People should always check identification before allowing anyone into their home.
"If they do come across anything suspicious we would urge them to let us know."
It is believed the men could have had a vehicle parked nearby.
Anybody who saw three men in a car or has any other information is asked to contact Pc Gerry Lenihan on 01484 436664.