MONTREAL - The water in LaSalle and Lachine is not safe to drink.

The city of Montreal issued a boil water advisory on Sunday evening for the two boroughs, and is still in effect.

"We didn't want to take any risk and that's why we collected samples and probably the situation will be back to normal as of tomorrow afternoon. But it depends on the analysis that will be done on these two samples that have to be taken 24 hours apart," said Jacques-Alain Lavallee of the City of Montreal.

"Once we have analyzed those two samples then we will know what to do."

Residents of most of LaSalle and Lachine should boil their water for at least one minute before drinking it, using it for cooking, or brushing their teeth. Hand washing, bathing, and washing clothes and dishes do not require boiled water.

All of Lachine except for the Ville St. Pierre neighbourhood is affected.

In LaSalle, residents in two areas south of St. Patick must boil their water: west of Dollard Ave. as far south as 80th Ave.; east of Dollard Ave. to Lapierre St. and north of Newman Blvd.

City officials blamed a problem at a water treatment plant in LaSalle, saying water treatment chemicals were not properly used on Sunday.

About 80,000 people are affected by this notice.

For more information, call the city at 3-1-1, the Lasalle borough at 514-367-1000 or view this notice for Lasalle or this notice for Lachine.

Multiple water advisories in recent months

This is the at least the second time this year LaSalle residents have had to deal with a boil water advisory.

During the last weekend in May, a large section of the borough was affected.

Meanwhile this is the fourth boil water advisory in the Montreal area since August, all for unrelated reasons.

In August tests on a reservoir used by residents of St. Bruno de Montarville showed signs of e. coli contamination, because of improper installation of a temporary water main.

In September Lachute ordered a boil water advisory because water was not safe to drink.

And in October West Island residents complained of dark, foul-smelling water after a failure at the Pointe Claire water filtration plant.

That advisory was due to low levels of chlorine, aggravated by an intake pipe being clogged with decaying weeds and leaves.

UPDATE: The boil water advisory ended late Wednesday afternoon.