Up to 40,000 residents on the NSW Central Coast were told to boil drinking water, after E. coli was previously detected in a reservoir, but new testing has cleared the supply of contamination.

Residents in some NSW Central Coast suburbs have been advised to boil their tap water due to the possible contamination of the local water supply with E. coli bacteria. A "boil water alert" was issued by Central Coast Council last night after recent samples detected the presence of E. coli bacteria.

An alert issued by Central Coast Council said samples from the drinking water supply contained E. coli bacteria.

Up to 40,000 Aussies are being urged to boil their water after E. coli was discovered in their water supply.  Residents on NSW's Central Coast have been advised to boil their water after the harmful bacteria was found during a routine testing of the Terrigal Reservoir.

A number of affluent southern Central Coast suburbs are being urged to boil water with recent investigations by council revealing the presence of a harmful bacteria at the Terrigal Reservoir.

People on the Central Coast have been instructed to boil tap water after testing detected E. coli bacteria in the local water supply.