Worthing residents have reported a number of calls where con men ask for money to pay for equipment for drainage works.
They say they are carrying out drainage works and they need cash to pay for specialist machinery.
This is usually followed up by several phone calls by someone pretending to be from the drainage company asking for the money to be sent to them.
Detective Sergeant Russ Burgess said: “This is a scam aimed at obtaining large sums of cash out of residents by telling them they need to pay for equipment for essential drainage work to their property to be carried out.
“A man usually calls at the house, asks for the victim’s phone number and then follows it up by several phones asking for large sums of money. Don’t let any strangers into your home, give out your phone number or withdraw money to give to them. Phone police on 101 to report any suspicious behaviour.”