Sewer backup coverage helps protect your home and belongings from costly and potentially hazardous wastewater that may enter your home through the toilet, sink, floor drains and other plumbing fixtures. Sewer backups may occur when the city’s sewer system, your home’s drainage system or your septic system becomes overwhelmed. Most residential insurance policies typically don’t cover sewer backup unless you have coverage for this type of water damage.
Our editorial team reviewed the Insurance Bureau of Canada’s water and flood guide, Government of Canada’s backwater-valve guide, and the Public Health Agency of Canada’s flood-health guidance while preparing this guide.
What Is Sewer Backup Coverage?
Sewer backup insurance is an add-on to your basic home insurance policy. It’s designed to protect you from damage caused to your home and belongings by a sewage backup. Other common names for this coverage are water backup coverage and drain line backup coverage.
Some situations where sewer backup coverage may come in handy include:
- Your sewer, septic tank, or storm drain discharges water
- A sewer backup damages your home and belongings
- Your sump pump or similar equipment overflows
Is Sewer Backup Coverage Part of Your Home Insurance Policy?
Sewer backup coverage typically isn’t part of your home insurance policy. Most home insurance policies only cover water leaks. You need to pay extra to get sewer backup coverage. You might also need extra insurance coverage for flooding.
Fortunately, it’s usually not as expensive as your main home insurance policy. Getting one is a good idea, especially if you live in an area prone to sewer backups.
What Sewer Backup Insurance Covers
Sewer backup insurance covers damages and repair costs caused by a sewer backup. It usually includes the following:
- Damage to your house or building
- Damage to furniture and belongings
- Sewer line repair costs
- Water cleanup costs
Coverage details may vary between providers, so double-check with your insurer to confirm what your insurance covers.
Sewer Backup vs Overland Water vs Groundwater
Lots of water-based damage coverage isn’t included within broad and comprehensive home insurance policies. To help you understand the different types of water damage to your house, here’s a table outlining the differences between sewer backup, overland water, and groundwater damage:
| Sewer Backup | Overland Water | Groundwater | |
|---|---|---|---|
| Where the water comes from | Toilets, sinks, and drains connected to sewer lines. | Freshwater flowing above ground. | Underground, generally through your home’s foundation. |
| Example Scenario | A clog in sewer pipes causes your toilet to spew wastewater. | Heavy rainfall causes the nearby river to overflow, flooding your neighbourhood. | After heavy rainfall, you find water stains on your basement walls. |
| Covered Under | Sewer backup coverage | Overland water coverage | Groundwater coverage |
| Coverage Type | Available as optional protection. | Available as optional protection. | Available as optional protection. |
Read More: Compare Overland Water Coverage and Flood Insurance
Should I Get Sewer Backup Coverage?
Estimate how much a sewer backup could cost. What would it cost to replace possessions and improvements contaminated by a backup, plus cleaning, drying and reconstruction? Include temporary living expenses and keep the endorsement’s limit and deductible in mind.
If you have a basement, consider whether it has finished floors and walls, expensive mechanical equipment, a bedroom, an office or rented living space.
Get information from your municipality about flooding history and whether you live in an area with combined storm and sanitary sewers. Ask about rules for disconnecting downspouts from storm drains, permit requirements for backwater valves and any programs that help pay for installation.
Tell your insurer about previous sewer backups and whether you’ve installed a backwater valve or sump pump with a battery or generator backup. Don’t assume these improvements will result in a discount or change your coverage.
How Common Is Sewer Backup Protection in MyChoice Quotes?
MyChoice’s analysis of thousands of quotes since early 2026 found sewer-backup coverage in 92.4% of Toronto quotes. It also appeared in 86.4% of quotes in Sudbury, 80.4% in Brampton and 73.0% in Calgary. When quotes itemized sewer-backup protection, the median cost was $129 per year.
Although a quote may include sewer-backup coverage and show its cost, you still need to decide whether the limit is adequate. Review the limit and deductible and make sure you understand how water must enter your home for the loss to be covered. Consider the cost of a finished basement, valuable items stored there and temporary accommodations.
How Much Sewer Backup Coverage Do I Need?
Calculate your total exposed value, including finishes, contents, appliances, temporary living costs, debris removal and decontamination. Do not rely on national averages.
Review your policy to determine what is included. Some policies have separate limits for contents and the building, while others apply a sewer-backup sublimit. For example, you may have a $25,000 sewer-backup endorsement but a documented exposure of $60,000. In this example, at least $35,000 would remain above the coverage limit.
Common Causes of Sewer Backup
- Heavy rainfall or melting snow that causes municipal storm sewers or combined sewer systems to back up
- Grease, paper, wipes or other material blocking private drains or the public sewer
- Tree roots entering broken, older or failing private sewer lines
- Broken, collapsed, shifted or restricted private sewer lines
- Failure or improper maintenance of a sump pump or backwater valve, depending on how the endorsement defines the resulting water damage
Spotting Signs of Sewer Backup
Slow drains are the easiest sign to spot. If only one drain is slow, it may be an isolated clog. If more than one drain is slow at the same time, you could be dealing with a larger issue.
Other signs include gurgling drains, sewage-like odours, toilets that react when other fixtures are used and water backing up near floor drains. If you notice these signs, stop using the affected fixtures and call a qualified plumber. Keep people and pets away from areas where sewage is entering the building.
Why Sewer Backup Water Is Dangerous
Do not touch contaminated water. Follow instructions from local authorities. Contaminated items may require special handling by a professional restoration company. Do not walk through water that may conceal structural damage. Never enter flooded areas where electrical equipment may still be energized.
Floodwater may contain untreated sewage, chemicals and other contaminants.
How to Prevent Sewer Backups
- Have a licensed plumbing professional determine whether a backwater valve is appropriate, where it should be installed and whether local permits or inspections are required. Follow the product manual and applicable local requirements. The federal guide recommends inspecting a backwater valve at least once a year in the spring and cleaning it at least twice a year.
- Test and maintain sump pumps regularly. Have a backup or auxiliary power source available in case of a power failure.
- Do not dispose of wipes, oils, fats, grease or anything else that should not enter your drains.
- Keep roof drainage and other surface water flowing away from the foundation, subject to local requirements.
- Correct grading problems and elevate valuables above anticipated water levels.
Read More: See How Sump Pumps Relate to Home Insurance
Making a Sewer Backup Insurance Claim
- Your safety should be the priority. Avoid walking through sewage or risking contact with live electrical wiring. Leave the building and call the appropriate emergency service or utility company if necessary.
- Once it is safe, take steps to prevent further damage and avoid using affected drains.
- Call your insurer as soon as possible. Describe what you observed without speculating about the cause. Ask about approved emergency services, coverage limits, deductibles and how the covered loss will be determined.
- Take photos of the backup point, high-water marks, affected areas and damaged belongings. Unless an item presents a safety risk, don’t throw it away without the insurer’s approval. Save repair and mitigation invoices, temporary living expenses, the plumber’s report and any utility reports.
Read More: Read How Home Insurance Treats Water Leaks