Three new water samples tested positive for E. Coli and coliform bacteria contamination in White Rock on Monday, meaning a boil water advisory covering the entire town could last through Saturday.
One of the Merklin reservoirs and sites directly east and south of it have tested positive for the contaminants, said David Rector, spokesman for EPCOR, the utilities company that operates the city's water system.
"We immediately shut down that reservoir. We are draining it right now," he said.
Once drained, the water left on the inside will be tested and a thorough investigation will take place, according to Mr. Rector. Subsequently, the tank will be chlorinated, disinfected, rinsed and refilled on Tuesday.
The cause of the contamination will not be known until EPCOR representatives are inside the reservoir. Mr. Rector said common sources of E. Coli and coliform are dead mice or birds that get inside the tank.
The advisory came down on Friday after a test site on Moffat Lane came back positive for both E. Coli and coliform.
The 20,000 residents of the Vancouver suburb were advised, until further notice, to boil their water for one minute before drinking, washing foods, doing the dishes, making ice or cooking. The water is safe for washing clothes and bathing, according to EPCOR.
Approximately 80 South Surrey residents are also affected by the advisory and have received hand-delivered notification of the danger.
"It will stay in place today and the direction from Fraser Health is we need three days of negatives to lift it," Mr. Rector said on Monday afternoon.
The contamination first showed up in water test results on Thursday, according to Dr. Elizabeth Brodkin, medical health officer for the Fraser Health Authority.
The 100-millilitre sample showed one count of both coliform and E. Coli.
"No level of E. Coli is acceptable," Dr. Brodkin said. "E.Coli is a marker for fecal contamination."
Due to EPCOR's good track record, the health authority ordered a further test to verify the results, she said. When it came back positive for coliform and E. Coli on Friday a boil water advisory was issued.
There have been no signs that anyone has become sick due to water quality, according to the health authority.
EPCOR and the Fraser Health Authority regularly test the water system, collecting at least 23 bacteriological samples per month which are then analyzed by the B.C. Centre for Disease Control.
In order for the boil water advisory to be lifted, EPCOR will have to bring three separate negative tests from the original site and the contamination source to the Fraser Health Authority, and will have to prove they have thoroughly investigated the problem, Dr. Brodkin said.