A summer downpour or a fast spring thaw, and sewer water comes up through the basement floor drain. A backwater valve in Brossard is one of the most useful safeguards for any home with a basement, as long as it’s properly installed, in the right spot, and maintained. Here’s what to know before calling a plumber.
What is a backwater valve?
A backwater valve is installed on your drain piping. It lets wastewater flow from the house to the municipal sewer, but closes when water tries to flow back in. Think of it as a one-way door.
It’s typically installed on the drains of fixtures below street level: floor drain, basement toilet, shower, sink or washer. There are normally open and normally closed models; the right one depends on your plumbing layout and the Code.
Why a backwater valve matters
During heavy rain or snowmelt, the sewer system can be overwhelmed. If the level rises above your basement drains, water finds the lowest exit: your home. The result:
- contaminated water on floors, walls and stored belongings;
- health risks and mould if drying is delayed;
- costly cleanup and repairs;
- an insurance claim, and possibly a higher premium.
A working valve greatly reduces that risk. It does not stop water coming through the foundation, windows or a high water table; that’s the job of a weeping tile system and sump pump.
What the rules require
Plumbing in Quebec falls under Chapter III (Plumbing) of the Construction Code, administered by the Régie du bâtiment du Québec (RBQ). Article 2.4.6.4 of that chapter deals with backflow from sewers, and the RBQ has published an interpretation on where normally open backwater valves may be installed.
Many Quebec municipalities have bylaws requiring owners to install and maintain water-damage protection, including backwater valves, and several state that the city isn’t liable for damage if the valve is missing or poorly maintained. As of November 2, 2026, we could not confirm online the exact Brossard bylaw or any subsidy for installing a valve. Before starting, contact Services Brossard (450 923-6311 or services@brossard.ca, as listed on the City’s website) about current requirements, permits and any assistance program. See also our guide to renovation permits in Brossard.
Installation: hire an RBQ-licensed plumber
Installing a valve often means breaking the basement slab to reach the pipe, then patching it properly. This isn’t a DIY job. Hire a plumbing contractor holding an RBQ licence. In Quebec, master plumbers belong to the Corporation des maîtres mécaniciens en tuyauterie du Québec (CMMTQ), which prepared a good-practices sheet on backwater valves with the RBQ.
| Check | Why |
|---|---|
| Valid RBQ licence | Searchable in the RBQ licence holder registry. |
| Inspection first | All fixtures below street level and pipe condition must be identified. |
| Valve type | Normally open or closed, depending on the Code and your setup. |
| Maintenance access | The valve must remain reachable through an access cover. |
| Written quote | Concrete work, restoration, permit and warranty: included or not. |
Find a pro on our Plumber in Brossard page, or compare quotes through our renovation quotes guide and estimations.pro.
Yearly maintenance
A neglected valve can get stuck open with debris and fail when you need it most. Check it at least once a year, ideally before storm season:
- open the access cover and remove debris;
- make sure the flap moves freely and closes fully;
- inspect the seal;
- keep the access clear of furniture, boxes and flooring;
- follow the manufacturer’s instructions, or call a plumber.
During a storm, avoid running the washer or dishwasher: with some closed valves, your own wastewater has nowhere to go.
Home insurance and sewer backup
In many home insurance policies, sewer backup coverage isn’t included by default and is added as an endorsement. Some insurers ask whether a working backwater valve is installed before offering it, or factor it into the premium. Check your policy and limits, keep the installation invoice and a record of maintenance, and if damage occurs, take photos and notify your insurer quickly. Quebec’s Autorité des marchés financiers publishes neutral information on home insurance. Landlords can find more tips in our guide to buying a plex in Brossard.
FAQ
Does my house already have one?
Look for an access cover in the basement floor near the main drain. A plumber can confirm, with a camera if needed.
Does it stop all water problems?
No. It only blocks water coming back up from the sewer. Foundation seepage needs other solutions.
Is there a Brossard subsidy?
We found no confirmed program online as of November 2, 2026. Ask Services Brossard before doing the work.
How often should it be maintained?
At least once a year, and after any backup or plumbing work.
Sources: Régie du bâtiment du Québec, Construction Code Chapter III and its interpretation on normally open backwater valves; City of Brossard website (Services Brossard contact). Consulted November 2, 2026. General information only.
brossard.city is an independent guide, not affiliated with the City of Brossard. Information is provided for general guidance only; check with official sources before making any decision. Spotted an error? Let us know.