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The drainage system inside your house channels wastewater from your sinks, laundry, shower and toilet through pipes that connect to a main sanitary sewer pipe under your basement floor. This pipe leads to the property line where it connects with the EPCOR main line.

What is a backwater valve?

A backwater valve is a device that is placed on the main sanitary sewer pipe in your home to prevent sewage from flowing back through the pipes from the mainline and flooding your basement. It does this by automatically closing its flap.

A backwater valve is an important tool for protecting your home, but it does require maintenance to ensure it remains effective.

Can't find your backwater valve?

If you can't locate your backwater valve, your home might not have one. Backwater valves were not required in homes built before 1989. A backwater valve is important to protecting your home, you should consider installing one and you may be eligible for our backwater valve subsidy program.

How do you maintain a backwater valve?

Inspecting and cleaning your backwater valve is essential home maintenance to ensure it is working correctly. Make sure you have a flashlight, safety glasses, and rubber gloves.

  • Locate your backwater valve and remove the plug or panel.
  • Shine the flashlight around the area and look for debris. Debris stuck in the gate can cause the sewer backwater valve to stop working.
  • Clean the area. Flush the valve with a bucket of water to clear debris from the gate area. If that doesn't work, scrub the area to remove it.
  • Once clean, move the gate back and forth to make sure it moves without any problems. If it's stiff or you see rust, oil it a little bit.
  • Check the O-ring on the backwater valve. If it's cracked or damaged, replace it.
  • Replace the plug or panel on top of the valve.

Flood prevention resources

​Backwater valve subsidy program

You could be eligible for funding for a backwater valve installation.

Learn more

​Flood prevention home inspection

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