Residents in North Kesteven, Lincolnshire, are urged to be on their guard following two distraction burglaries in Leasingham and Bassingham.
In both cases elderly residents were targeted by bogus callers posing as utility workers.
On Friday August 2, a man wearing a fake ID card cold-called a woman in her 80s in Bassingham.
He claimed to be working in the area and said he needed to turn her water off.
While pretending to do so under her kitchen sink, two other men searched the house before making off with jewellery and a purse containing bank cards and the victim's pension card.
The victim was unable to give a description of the suspects.
On Tuesday August 6, a couple in their 90s who live in Leasingham were targeted in a similar fashion.
The men claimed to be from a water company and items were stolen from the property.