Residents of the Comox Valley on Vancouver Island have been told to boil their drinking water after tests detected E. coli in the regional district' s water system.

The notice, which was issued on Thursday, covers all Comox Valley water system customers in the City of Courtenay, the Town of Comox, Comox Valley, Arden, Marsden Campco, Greaves Crescent and England Road water local service areas and those who obtain water from the Comox Valley water system.

"Until further notice, water from the Comox Valley water system should be held at a rolling boil for one minute and cooled before it is consumed. For your safety, only boiled or bottled water should be used for drinking, making ice or fountain drinks, washing dishes, brushing teeth, or preparing foods that will not be cooked," said the advisory.

"The Comox Valley Regional District and the Vancouver Island Health Authority are working together to resolve the situation. Once the water is safe to drink, the boil water notice will be rescinded," it said.

Dr. Charmaine Enns, the medical health officer for the Vancouver Island Health Authority, said the boil water advisory won't be lifted until the source of the E. coli is found.

"We need to see at least three negative samples that are consecutive for any bacteria or E. coli, and the water supplier is obviously going to have to do an investigation on trying to sort out where that possible contamination came from, and then any corrective measures can be taken," she said.