Sewer Backup Coverage in Quebec: What’s Covered?

A heavy summer storm over Saint-Jérôme, a fast spring thaw in Mont-Laurier, a rain-on-snow event in Blainville: in the Laurentides, sewer backups tend to come all at once, when municipal networks are overloaded. Within minutes, water and sewage can come up through a basement floor drain, a shower or a toilet. If your basement is finished or rented, the damage can be serious.

Many homeowners only learn after the fact that their policy didn’t include sewer backup, or that their claim was complicated by a missing backwater valve. This guide explains the endorsement, how it differs from flood coverage, what municipal bylaws require, and how to reduce the risk.

Key takeaways

• Sewer backup is optional coverage you add to your policy, not standard.
• It covers water entering through the drainage system (drains, sewer pipes, sump), not water flowing in from outside.
• Overland flood (rivers, lakes, surface water) is a separate optional coverage.
• Endorsements often have their own limit and sometimes a separate deductible.
• Many Quebec municipalities require backwater valves and annual maintenance, and may not be liable if you don’t comply.
• Prevention (valve, sump pump, grading, downspouts) protects both your basement and your insurability.

What is the sewer backup endorsement?

In Quebec, insurers and brokers call it the avenant refoulement d’égout. An endorsement is an addition to your policy that changes or extends coverage. According to the Insurance Bureau of Canada’s brochure Water Damage: Are You Protected?, sewer backup coverage protects against damage from a sudden backup of sewers, pipes, drains, septic systems or sump pumps, and it is available as optional coverage added to a home, condo or tenant policy. In some areas, coverage may be limited.

In its 2026 guidance after flooding in Ottawa, reported by Insurance-Canada.ca, the IBC repeated that basement water damage from a sewer backup is only covered if you have bought specific, optional sewer backup coverage, and that coverage varies by insurer and policy.

Is sewer backup covered by default?

Usually not. Some insurers bundle it into premium packages, but you shouldn’t assume it’s there. Look in your policy declarations for a line mentioning sewer backup, water backup or refoulement des égouts. If you don’t see it, call your insurer or broker.

Sewer backup vs overland flood vs plumbing water damage

Water damage claims fall into different categories, and each is handled differently.

Type of water	Where it comes from	Usual coverage
Sudden plumbing leak	Burst pipe, water heater, appliance hose inside the home	Included in most home, condo and tenant policies
Sewer backup	Water or sewage pushed back up through drains, sewer pipes or the sump	Optional endorsement
Overland flood	Rivers, lakes, surface runoff entering at ground level or through openings	Optional coverage; may be unavailable in high-risk zones
Groundwater seepage	Water through foundation walls or floor	Varies; often linked to the overland/flood endorsement or excluded

Some insurers combine sewer backup and overland water in one endorsement; others sell them separately. If you live near the Rivière du Nord, the Rouge or a lake, ask about both. For a broader look at all water coverages, read our guide on water damage, sewer backup and flood insurance in the Laurentides.

Limits and deductibles

A sewer backup endorsement usually has its own maximum amount, which can be lower than your main building and contents limits. Some policies also apply a separate deductible to water claims. When comparing quotes, ask:

1. What’s the maximum payable for a sewer backup claim?
2. Is the deductible the same as the rest of the policy, or higher?
3. Does the limit cover both the building and contents, or each separately?
4. Are finished basement materials, like flooring and drywall, covered at replacement cost?
5. Is a working backwater valve or sump pump a condition of coverage or of a discount?

If you finished your basement or rent it out, a low limit might not be enough. We don’t publish typical amounts because they vary between insurers, so read the declarations page carefully.

Backwater valves and municipal bylaws in Quebec

A backwater valve (clapet antiretour) is a device installed on a drain pipe that closes automatically when water or sewage flows back from the municipal sewer, preventing it from reaching basement fixtures.

What municipal bylaws require

Many Quebec municipalities have adopted bylaws requiring owners to install and maintain these devices. One example in the Laurentides is the Municipalité de Lac-des-Écorces, near Mont-Laurier. Its bylaw 273-2022 on protection against water damage requires the owner of any building connected to the sanitary, storm or combined sewer to install the backwater valves needed to prevent backflow, regardless of when the building was built. It requires valves on branches serving fixtures located below street level, including floor drains, foundation drains and the sump pump discharge, and it requires the owner to inspect and maintain the valve every year. Valves must stay accessible.

The bylaw also relies on section 21 of Quebec’s Municipal Powers Act (Loi sur les compétences municipales): a municipality isn’t liable for damage to a building or its contents if the owner failed to install or maintain a required protective device. Many other municipalities have similar rules, but the details differ. Contact your town hall, whether in Saint-Jérôme, Mirabel, Sainte-Agathe-des-Monts or elsewhere, for the bylaw that applies to you.

Plumbing code requirements

Installation must follow the plumbing chapter of the Quebec Construction Code. The Corporation des maîtres mécaniciens en tuyauterie du Québec (CMMTQ) explains in its technical sheet on backwater valves (posted by the Ville de Saint-Sauveur) that fixtures located below the level of the adjacent street must be protected, that valves must remain accessible for maintenance and cleaning, and that some municipalities restrict certain valve types. Hire a licensed plumber who knows your municipality’s rules.

Why the valve matters for insurance

Insurers may ask whether you have a backwater valve before offering the endorsement, and some may set conditions. A missing or blocked valve can complicate a claim against the municipality and, depending on your policy wording, your insurer may raise the question too. Keeping maintenance receipts is a good idea.

How to prevent sewer backup

The IBC recommends several simple measures:

• Install a backwater valve and keep it accessible and clean.
• Install a sump pump with a battery backup in case of power failure.
• Keep downspouts at least 6 feet (about 2 metres) from the foundation.
• Grade the lot so water flows away from the house.
• Store valuables and documents off the basement floor or upstairs.
• Use water-resistant materials in the basement, and raise the furnace, water heater and electrical panel where possible.
• Don’t pour grease down drains, which can block pipes.

Check with your municipality before connecting a sump pump or downspouts: many bylaws prohibit connecting roof drainage to the foundation drain.

What to do if your basement backs up

1. Stay safe: don’t enter standing water near electrical outlets or appliances, and cut the power if it’s safe to do so.
2. Call your insurer or broker as soon as possible.
3. Document everything with photos and video before cleaning.
4. Prevent further damage: start drying, but keep damaged items until the adjuster sees them or approves disposal.
5. Notify the municipality quickly if you believe the public network was at fault; bylaws and the law set short deadlines for notices.

Our step-by-step guide on how to file a home insurance claim in Quebec covers the claim process in detail. Tenants in basement units should also read our guide on tenant insurance in Quebec.

Frequently asked questions

Is sewer backup covered by home insurance in Quebec?

Not by default in most policies. It’s an optional endorsement you add to your home, condo or tenant policy. Check your declarations page or ask your insurer.

What’s the difference between sewer backup and flood insurance?

Sewer backup covers water coming up through your drains and sewer pipes. Overland flood coverage applies to water from outside, like rivers, lakes or runoff, entering at ground level. They are separate coverages, though some insurers bundle them.

Is a backwater valve mandatory in Quebec?

There’s no single province-wide rule for every home, but many municipalities require one by bylaw, along with yearly maintenance. The plumbing code also requires protection for fixtures below street level. Check your town’s bylaw.

Will my claim be refused if I don’t have a backwater valve?

It depends on your policy wording and the insurer’s conditions. A missing valve can also release the municipality from liability. Ask your insurer what conditions apply to the endorsement.

Does tenant insurance include sewer backup coverage?

Usually only if you add it. Tenants in basement or ground-floor units should ask for it, since their belongings are the most exposed.

Is the municipality responsible for a sewer backup?

Sometimes, but municipalities are often exempt when the owner didn’t install or maintain a required protective device. Strict notice deadlines also apply, so act quickly.

Have a question we didn’t answer? Contact us.

Sources: Insurance Bureau of Canada, Insurance-Canada.ca (IBC guidance), Municipalité de Lac-des-Écorces, bylaw 273-2022, CMMTQ fact sheet (Ville de Saint-Sauveur)

This article is for general information only and is not insurance advice. Laurentides Insurance Guide does not sell insurance. Always confirm with a licensed broker or your insurer.