Oct 15, 2026
When thunderstorms descended over Montreal’s West Island on June 20, some neighbourhoods received up to 170mm of rain, with most of it over a span of about four hours. Basements in Dollard-des-Ormeaux and Pierrefonds-Roxboro were full of contaminated water, and soaked drywall soon lined the curbs.
Nearly four months later, insurers have tallied $442 million in losses, but that figure only counts insured damage.
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Hundreds of residents have turned to the legal system, while others are hoping for some form of government relief. Neither route pays quickly, and both are conditional. However, for most homeowners, the fastest cheque is the one already written into their insurance policy.
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How much did the Montreal flood cost — and is the tally still rising?
The number has not yet been finalized. Catastrophe Indices and Quantification Inc. (CatIQ), a Toronto-based organization that tracks insured catastrophe losses in Canada, raised its estimate to $442 million in September. That figure rose 7.5% from August, mostly due to residential and commercial property claims. Another update is scheduled for Dec. 22.
And Montreal isn’t an outlier. Between June and August, CatIQ recorded six catastrophic events in Ontario and Quebec. Each was driven mainly by flash flooding and sewer backup as opposed to overflowing rivers. Together they generated more than 30,000 personal property claims; meanwhile, the same stretch in 2025 produced just one such event.
Caroline Floyd, a director at CatIQ, said that “in many ways, pluvial flash flooding events were the story of the summer.”
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Why can’t flooded homeowners just wait for the class actions?
Because a payout could be years away. A judge must first authorize the cases before they can proceed, according to attorney Jeff Orenstein. Consumer Law Group, a Montreal firm specializing in class actions, filed two applications in the Quebec Superior Court that seek authorization to sue the borough of Pierrefonds-Roxboro, the City of Dollard-des-Ormeaux and the City of Montreal. The applications allege the municipalities failed to upgrade aging drainage or add infrastructure such as retention ponds and sponge parks to prevent mass flooding events. None of these claims has been tested in court, and the municipalities declined to comment.
There’s also the bureaucratic concern of tight deadlines. Under Quebec municipal rules, notices of claim generally must be filed within 15 days of an incident in order to proceed.
Will Quebec’s disaster aid cover a backed-up sewer?
In the West Island case, no. Quebec’s General Financial Assistance Program Regarding Disasters is last-resort assistance for residents looking to receive some form of financial recompense that standard insurance doesn’t usually cover. Sewer backup qualifies only if a nearby watercourse overflowed first. A backup caused solely by heavy rain isn’t eligible. Also, if you have coverage for the disaster, you can’t apply at all.
Federal help isn’t any closer. A national flood insurance program targeted for April 2026 still has no launch date.
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Which add-ons actually cover a flooded basement?
A standard home policy doesn’t cover water rising through a floor drain or flowing in from outside. Sewer backup is covered only if you added that optional coverage to your policy, according to the Insurance Bureau of Canada (IBC), the national association representing private home, auto and business insurers. Overland flood protection is a separate add-on — however, it may be limited or unavailable in certain high-risk zones.
Limits matter too: the amount you choose may not cover all the damage. Mike Silverman, a Dollard-des-Ormeaux resident whose home has flooded twice since 2024, put his damage at $100,000.
Prevention is certainly helpful, but it’s not a guarantee. The lead plaintiff in the Pierrefonds-Roxboro case had backwater valves installed in 2022 and again in May 2026. Just a month later, on June 20, the basement still took in 30 centimetres of water.
What to do now
Before the next storm:
- Check whether your policy includes “sewer backup” and “overland water” coverage
- Compare each limit against what it would cost to gut and rebuild your basement in the aftermath of a flood
- Ask your broker whether a backwater valve or sump pump affects your premium or limits — sometimes it can qualify for a discount
- Check whether your municipality subsidizes backwater valve installation
If water gets in, the IBC says to photograph the resulting damage and any belongings you have to throw out, and keep every cleanup receipt. Be sure to call your insurer before applying for government aid, as you may not qualify for it. In Quebec, it’s also important to file a notice of claim with your municipality within 15 days of the incident.
The lawsuits, if successful, may eventually push cities to rebuild their drainage. Until then, the gap is yours to close. As Liam McGuinty, IBC’s vice-president of federal affairs, stated: “Flooding is Canada’s costliest and most pervasive climate risk.”
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Writer and editor based in Toronto with experience in personal finance, insurance, arts and culture and branded content.
