Intense summer storms have flooded thousands of basements across Toronto and the GTA in recent years. When the municipal sewer system is overwhelmed, wastewater can flow backward into homes through floor drains, toilets and laundry tubs. A backwater valve is one of the most effective ways to protect your basement, and the City of Toronto helps pay for it.

What a backwater valve does

A backwater valve is a device installed on your home’s main sewer line. Under normal conditions, wastewater flows out to the city sewer. If the sewer backs up, a flap inside the valve closes and blocks sewage from flowing into your basement.

Why the risk is rising

• More intense rainfall: short, heavy downpours can exceed what older sewers were designed to handle.
• Combined sewers: many older Toronto neighbourhoods have sewers that carry both stormwater and wastewater.
• More paved surfaces: roofs, driveways and roads send water into sewers faster than lawns and gardens.

Toronto’s Basement Flooding Protection Subsidy

The City of Toronto’s Basement Flooding Protection Subsidy Program offers eligible homeowners money toward a backwater valve, a sump pump and disconnecting the downspouts and foundation drains from the sewer. The backwater valve portion has been up to $1,250. Amounts and conditions can change, so confirm the current rules on toronto.ca before you hire a contractor. Key conditions typically include:

• Getting the required plumbing permit from the city.
• Using a licensed plumber.
• Applying within the deadline after installation, with receipts and inspection documents.

Other GTA municipalities and some insurers also offer incentives or premium discounts. Check with your city and your home insurance provider.

How much does installation cost?

Costs vary with your home’s plumbing, the depth of the sewer line and whether concrete must be cut. Get at least two or three written quotes from licensed plumbers and make sure the price includes the permit and inspection.

Maintenance tips

1. Check the valve every few months and after major storms.
2. Remove debris and make sure the flap moves freely.
3. Never pour grease or oil down drains.
4. Keep the access cover reachable; do not build over it.

More ways to reduce flood risk

• Direct downspouts at least two metres away from your foundation, onto your lawn or into a rain barrel.
• Grade soil so water flows away from the house.
• Store valuables off the basement floor in waterproof containers.
• Review your insurance policy for sewer backup and overland water coverage.

Living in an older home? Also read how older Toronto homes may contain asbestos. More local updates are in our Toronto News section.