Stonington residents are urged to boil water before consumption, police said.
A drinking water advisory has been issued by the Westerly Water Department effective immediately.
Police said this is a precautionary boil water advisory for all Westerly Water customers in the Pawcatuck section of Stonington, in addition to Westerly.
"Bring all water to a boil, let it boil for one minute, and let it cool before using, or use bottled water. Boiled or bottled water should be used for drinking, making ice, brushing teeth, washing dishes, and food preparation until further notice. Boiling kills bacteria and other organisms in the water," Stonington police said.
The water department said Westerly's Bradford 2 Wells tested positive for a fecal indicator.
General guidelines on ways to lessen the risk of infection by microbes are available from the EPA Safe Drinking Water Hotline at (800)426-4791.