Health officials in Saint John are blaming an inadequate water treatment system for a boil water order that is affecting 40,000 people in the southern New Brunswick city.

Wednesday's winter storm dumped 70 millimetres of rain on the city, creating flooding and stirring up sediment in Latimer Lake. The lake serves as the water reservoir for residents living east of the Reversing Falls Bridge.

"It [the sediment in the water] diminishes the effectiveness of chlorine as a disinfectant," said Dr. Scott Giffin, a medical officer for health for Region 2 in Saint John. "It makes it difficult to detect bacteria in the system."

A modern water treatment system may have prevented the problem, said Brent McGovern, the city's water and waste manager. But Saint John's current system doesn't do much more than filter out sticks and chlorinate the water, he said.

"We recognize we need to have higher levels of treatment, and higher levels of treatment may have avoided a boil water advisory," McGovern said.

City council has said that getting a new water treatment system is a priority and has been examining moving forward with a public-private partnership. But the construction of two new filtration plants is estimated to have a price tag of between $110 and $140 million for the city and some officials have said it would not be financially feasible until at least 2012.

City keeping close watch

For now, the city will just monitor the situation closely, said McGovern. He said hopefully the boil water advisory will be lifted by Monday morning.

Until the order is lifted, residents and businesses are being advised to boil water for at least one minute before drinking, making ice, washing vegetables or brushing teeth. Bathing and washing dishes with soapy water is safe.

A weather-related boil order in the city is rare, McGovern said. "I don't recall Saint John ever having a boil water order as a result of turbidity level increases." (Turbidity is a condition of water that has been stirred up and made cloudy by silt or organic matter).

The order is an inconvenience, said Charlene McDonough, who loaded up her car with six dozen bottles of drinking water to get her through the weekend.

It has meant good business for those selling the fluid, said Robbie Barr, a grocery store manager in Saint John.

The store has already sold out of its four litre jugs of water and customers are now stocking up on the 18 litre water cooler-style containers.

"Everybody's got a bottle of water in their cart," Barr said. "We sell a lot of water but it's definitely moving out way quicker than it normally would."