Despite high levels of cancer-causing chemicals being found in Saint John's water, city council says it can't afford a better treatment plant.

"The citizens of Saint John can't afford $110 million over what they pay now," Mayor Norm MacFarlane said Thursday. "They just can't afford that."

It's estimated the construction of two new filtration plants would cost the city between $110 million and $140 million.

To get that money would require lobbying the federal and provincial governments for funding, said MacFarlane.

Earlier in the week, city staff discovered higher than acceptable levels of the water sterilization byproduct trihalomethane at two sites in Saint John.

The water is still safe to drink, said officials from the city's water and sewer department. But the discovery promoted health officials to again stress that the city needs a full filtration system to ensure the best possible water for its residents.

A treatment system with full filtration isn't expected to be financially plausible in Saint John until at least 2012.

Chlorination is currently the only safeguard for the city's water, said Dr. Scott Giffin, a medical officer of health for Region 2 in Saint John.

"The chlorination system is rigged with alarms so if it fails, it should alarm. But we've already had episodes in which that didn't happen," said Giffin, "and when you have something like a lightning strike, that can disable these sort of things and it can be sometime before anybody knows we're not getting chlorinated water."

Water is supplied to the city from Spruce Lake and Loch Lomond Lake and is susceptible to contamination from animals, human dumping, the nearby airport and roads.

"If there was some sort of accident that happened that ended up in the water supply, then we'd have no way to manage that without letting it come through the system," said Giffin.