Water main that broke and flooded Montreal streets was almost due for inspection, city says

The large water main that burst and submerged streets in south-central Montreal in spectacular fashion last Friday was due to be inspected in the coming months, according to the city.

The water main break, which happened at around 6 a.m., caused flooding, disrupted the rush-hour commute and led to a boil-water advisory affecting about 150,000 residents in the eastern half of the island.

That advisory was lifted on Saturday night.

On Monday, Montreal Mayor Valérie Plante met with reporters near the corner of Frontenac and Notre-Dame streets, close to the site where the break occurred. She said it’s still not clear what caused the break.

Chantal Morissette, the city’s director of water services, said the water main that broke was last inspected “in 2017 or 2018.”

“There was deterioration there and that’s the reason why the water main was under surveillance,” Morissette said. “The next inspection was coming up.”

She said a five-to-seven year delay between inspections is the norm, depending on the state of a water main.

“The information we had at the time was that it was deemed able to continue providing the service it was built to provide,” Morissette said, referring to the water main’s last inspection several years ago. 

“If it had been deemed critical to the point that we needed to shut it down, we would have done it.”

Every year, the city inspects about 15 kilometres of its underground water supply network, according to Morissette. She said 90 per cent of the network is in good shape, and the other 10 per cent is in either “bad or really bad shape.”

The city says it needs inspect the water main and determine what led to the break, before finishing repairs. The timeline for this is unclear.

Plante said the city was relieved that water service was not interrupted. She and Morissette said the Rosemont reservoir, which was put back in service in the last few years after being shut down for four decades, continued to funnel water to the east end while crews worked to stop the massive outpour.

Morissette said the reservoir can continue to function in this way for a few months, if…