Backwater valve

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.

Did you know?

When the backwater valve closes the sewer line, you should not use the toilet, sink, shower, washer, or dishwasher. Until the flap is reopened, the wastewater will have nowhere to go except up the floor drain and into your basement.

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.

Interior backwater valve maintenance
Exterior backwater valve maintenance

For successful backwater valve maintenance, you must complete a visual inspection of the entire valve area to determine if there is any debris.

To do this you will need to remove the cleanout plug from the top of the valve making sure the O-ring stays with the plug/cap.

Using a flashlight, inspect the area above and under the valve gate carefully. Most of the time, the malfunctioning of the valve is the result of debris stuck around the gate hindering its free movement.
Wear a pair of rubber gloves and clean the area thoroughly; in some cases, a fast jet of water can help you in cleaning the gate area of the valve.
Once the gate is thoroughly cleaned, move the gate back and forth to see if it is moving without restrictions.
You should also check the O-ring of the backwater valve plug/cap. If the O-ring is not in good condition, replace it.

For successful backwater valve maintenance you must complete a visual inspection of the entire valve area to determine if there is any debris.

To do this you will need to remove the cleanout plug from the top of the valve making sure the O-ring stays with the plug/cap.

Most of the time, the malfunctioning of the valve is the result of debris stuck around the gate hindering its free movement.
A fast jet of water can often help you in cleaning the gate area of the valve, this can be done by lowering a hose and rinsing the gate area.
If adequate cleaning cannot be performed, then removing the valve flapper with stem pipe is recommended for further cleaning, this may require contacting a qualified contractor.
You should also check the O-ring of the backwater valve plug/cap. If the O-ring is not in good condition, replace it.

Backwater valve

What is a backwater valve?

Can't find your backwater valve?

Did you know?

How do you maintain a backwater valve?

Flood prevention resources

Backwater Valve Subsidy Program

Flood prevention home inspection

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