It took city crews hours to stop the torrent of water, which poured down Roland-Therrien Boulevard and into the basements of anywhere about 15 homes nearby, a spokesperson for the municipality said.
Some residents in the area reported that more than a metre of water had pooled in their basements.
The main — one of the largest water pipes in use in the city, at 76 centimetres in diameter — broke around 4:30 a.m. The water wasn't shut off until after 10 a.m. when crews were able to cut off the flow upstream. Personnel were still working underground after that.
Jean-Paul Lachance, who lives not far from the main break, had water halfway up his garage door when he woke up this morning.
"I hope they'll pay [to repair] some of it," he said.
He couldn't enter his basement because the water had risen to chest height, he said.
The city spokesperson advised homeowners to contact their insurance companies to find out about coverage.No damage estimate was available.