Every home is at risk of basement flooding, even if it has not happened before. Water in your basement is most likely to occur during a heavy rainfall, or when snow and ice is melting.

The good news is that you can take steps to help reduce or prevent it from happening.

The City offers a Basement Flooding Protection Subsidy of up to $3,400 per property.

Learn How to Apply

Watch Part 1 to reduce the risk of basement flooding by learning about your plumbing system, sewer cleanouts, overland flooding, cleaning blocked or plugged eavestroughs and disconnecting downspouts.

Watch Part 2 to learn about weeping tiles, sump pumps, sewer back-ups and backwater valves and the financial subsidies the City provides when you install flood prevention devices.

Know exactly what you are looking for? Click through the playlist below to view specific topic areas on basement flooding prevention.

Keep Water Out

  • Seal cracks or leaks in walls, floors, windows and foundations, and seal all window wells.
  • Clear eavestroughs and downspouts of leaves and other debris that prevent drainage.
  • Disconnect your downspouts from the sewer system, where feasible (without negatively affecting neighbouring properties or creating an area where water will pool on a sidewalk or driveway).
  • Make sure your disconnected downspouts are draining properly, ideally two metres from your foundation  walls.
  • Ensure the grading around your home slopes away from the foundation wall to help drain water away from your home (without negatively affecting neighbouring properties).
  • Increase the green space around your home with native plants and shrubs and install porous pavement to help absorb rainwater and melted snow.
  • Repair or replace damaged weeping tile systems.
    • Weeping tiles (also known as a French drain) are pipes with small holes located underground near your basement foundations to collect groundwater/rainwater.
    • Their purpose is for waterproofing basements.
    • Weeping tiles may drain into a solid pipe leading to a discharge or directly into a sump, where the water can be removed by a sump pump; however, it depends on your home’s drainage system.
    • Check the corners of your basement regularly and if the floor is damp/wet, your weeping tiles may not be working properly and may need to be repaired or replaced.
    • If your weeping tiles are connected to the sewer system, it is recommended that you disconnect it and install a sump pump and/or backwater valve (see Maintain Your Plumbing System under the Inside the House section below for more information).
    • If you are not sure if you have weeping tiles and/or if the weeping tiles are connected to the sewer system, please contact a licensed plumber for help.
  • Safely clear debris from roadside catch basins (grates) to help water enter the stormsewer.
  • Ensure drainage swales (shallow ditches) between properties are maintained and clear of obstructions.

Understand your Plumbing

Homeowners are responsible for plumbing from the property line to inside the home. You can hire a licensed plumber who conducts specialized testing or inspections, if needed, to help you identify the location and condition of key features of your household plumbing system:

  • Sewer service line (connects the plumbing in your home to the main sewer on the street).
  • Storm sewer main.
  • Backwater valve or sump pump; understand how to keep a sump pump maintained, and operational during power outages.

Maintain your Plumbing System

Ensure that your plumbing and drainage systems are in good working condition and understand how they function and how to maintain them.

  • Fix cracks, blockages or other condition problems.
  • Avoiding creating clogs:
    • Do not flush dental floss, Q-tips or other personal care products (i.e. “flushable” wipes, condoms or tampons). These should be disposed of in the appropriate bin.
    • Never pour fats, oils and grease down the drain. Dispose of small amounts in your green bin with material to absorb it.
    • Learn more about what not to flush and how to dispose of these items.
  • Hire a City-licensed plumber to:
    • inspect the full length of the sanitary pipe under the basement floor for weeping tile connections;
    • install a backwater valve or sewage ejector pump*, ensuring the weeping tile/foundation drain, if present, is connected downstream of the backwater valve;
    • install a properly-sized sump pump and piping.
  • Ensure proper and regular maintenance of the above devices in your home, including:
    • annual cleaning of the backwater valve via the clean-out ports;
    • consider installing a back-up power source for your sump pump.

*Sewage ejector pumps are not covered by the City’s Basement Flooding Protection Subsidy Program. The Ontario Building Code may not allow ejector pumps when the plumbing system is higher than the public sewer system.

Water can enter your home via many different places. The image below indicates how pipes can be configured; however, every home is different.

A complex diagram showing the plumbing system in a home. It shows the bathroom, basement as well as the system underneath the home. Water is entering the home via the external ground around the home, and leaving the home through a sanitary sewer.
Click to enlarge.


Two images of a backwater valve: one where the flap in the valve is open during normal operation and one where it is closed to block backflow from entering the home.
Click to enlarge.

Backwater valves are designed to close the sewer line during periods of extreme rain to prevent water from entering your home. When the valve is closed you should not use any plumbing fixtures (i.e. toilets, sinks, dishwasher, washing machine) because water will not drain and will backup into your home.

Backwater valves should be installed by a licensed plumber and require a building permit to be installed. It is also critical that backwater valves are maintained and regularly inspected according to product specifications.

Before work starts, verify that your plumber has a valid City of Toronto business licence using the Business Licence Lookup tool or by calling 416-392-6700.

The City offers a subsidy of up to 80% of the invoiced cost, up to a maximum of $1,250 to help offset the cost of installing a backwater valve. Learn more about the Basement Flooding Protection Subsidy Program

The plumbing system connected to a sump pump. One half of the picture shows the sump pump, the sump pump tank and access cover. The other half of the image shows the exterior discharge pipe exiting the access cover onto the outside of the home onto a patch of grass.
Click to enlarge.

Install a properly-sized sump pump to help pump water collected by the weeping tile system to an area outside. Make sure the sump pump empties onto a permeable surface at least two metres from the foundation wall.

Sump pumps can lose power during severe storms, so you may wish to consider a battery back-up. They also need to be inspected and maintained according to product specifications to ensure optimal performance.

The City offers a subsidy of up to 80% of the invoiced cost, up to a maximum of $1,750, to help offset the cost of installing a sump pump. Learn more under the Basement Flooding Protection Subsidy Program.