A crew works outside one of White Rock's reservoirs, trying to find a source of E. coli contamination. ((CBC))

The health authority responsible for White Rock, B.C., will review the practice of pumping water directly from an aquifer into the city's water supply without chlorination, a spokesman says.

"Is not chlorinating your water worth the disruption," Fraser Health Authority spokesman David Plug said Tuesday.

A boil water advisory was issued Friday for the city of 20,000, south of Vancouver after potentially deadly E. coli bacteria were detected in water at an aquifer well head.

On Monday, the bacteria were found in three other locations in the system.

The boil water advisory is expected to continue until at least next weekend as one of the city's two reservoirs is drained, disinfected and examined for possible sources of contamination.

"It was quite disheartening to get a positive result back after two days of 24 negative samples," said David Rector of Epcor Utilities Inc., the company contracted to provide White Rock's water.

Proud of untreated water

"We're looking for things like little holes or cracks where a mouse or a bird could have gotten in."

White Rock is the only jurisdiction within Metro Vancouver that does not chlorinate its water and that gets its water from the Sunnyside Uplands aquifer, which is accessed through six wells that vary in depth from 60 to 150 metres.

Many in the city are proud of the fact that the water is not treated and prefer the taste.

"I hope they're not going to put chlorine into the water," one resident told CBC News.

"It shouldn't be necessary if they sort this current problem out," said another. "It's been fine for years."

There will be no chlorination anytime soon, said White Rock Mayor Catherine Ferguson.

"That is something that is going to be dealt with and discussed in a debriefing with Fraser Health and Epcor and the city will be involved," Ferguson said. "But at this time, I don't know of any change that's going to happen."

The water supply for rest of the district is chlorinated after it leaves three rain-fed reservoirs on Vancouver's North Shore.