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Basements Can Flood for Many Reasons

While the City of Toronto is working to improve its complex system of underground pipes, sewers and catchbasins, these improvements alone cannot completely protect a home from basement flooding.

During heavy rain, the sewers can become overloaded. It is essential that homeowners take steps to help protect their home from basement flooding.


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.

There are a number of reasons why basements flood, including:

  • When stormwater or ground water seeps into the home (drainage failure) due to:
    • A crack or leak in your home’s foundation, basement walls, or basement windows or door
    • Poor lot grading or drainage
    • Failure of the weeping tile system (foundation drains)
    • Failure of a sump pump (in some homes) used to pump weeping tile water
    • Overflowing eavestroughs
    • Leaking or plugged downspouts
  • A sewer back-up caused by a blocked or overwhelmed sewer pipe.
    • Blockages are typically caused by items that are incorrectly flushed or poured down the drain. Tree roots and broken or cracked sewer pipes can also cause blockages.
    • Overwhelmed sewer pipes can happen during extreme rain. If the sewers fill beyond capacity, the water will travel backward in the sewer pipe and into the home.

If your basement is flooded, it is necessary that you take appropriate action to protect your home, your health and safety. The City also offers a Basement Flooding Protection Subsidy of up to $3,400 per property.

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.

You can take steps to help reduce or prevent it from happening.

Basement Flooding Protection Subsidy Program

The City offers owners of single-family, duplex and triplex residential homes a subsidy of up to $3,400 per property to install flood protection devices.

Basement Flooding Protection Program

The City is taking steps to stop the overloading of the sewer system and reduce basement flooding.

Mandatory Downspout Disconnection

Disconnecting downspouts from the sewer system is mandatory. It can reduce the risk of basement flooding and releasing polluted rainwater into our local waterways.

Preventative Maintenance

The City regularly inspects, cleans and maintains the sewer system to ensure it is in good working order.