A watermain break in Vaudreuil-Dorion on Monday afternoon cut off water to approximately 9,000 homes in the area as well as the city's industrial park and commercial district.
City officials say the break happened around 2 p.m. on St-Charles in front of the Cité-des-Jeunes secondary school.
"Water accumulated and covered both sides of the road," said city spokeswoman Jasmine Sharma, adding that the cause of the break is still unknown.
Water service was gradually restored Monday, and a boil water advisory was issued.
"As as a preventative measure ... we had to issue a boil water advisory. So citizens are being asked, once their water is re-established, to please boil their water for one minute before consuming it."
The water boil advisory, which is also in effect in some parts of Dorion, will last at least five days.