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Backwater Valve


Have you ever had water come up your floor drain in your basement? Do you want to know how to protect yourself?  A backwater valve is a device that can be installed on the internal or external plumbing in your home that prevents water from backing up into your basement.

These pictures show one type of approved backwater valve.  There are also other approved valves.

How Does it Work?

One type of backwater valve has a flap inside it that allows water to flow out of your home, but if water begins to flow into your home, this flap raises blocking the flow from coming into your basement.  There are other acceptable approved valves that also prevent flow from backing up into your basement.  Different valves are suited to different installations.

Protect Yourself

The most common source of basement flooding is water coming up through the floor drains.  The best way to protect your home from this happening is installing a backwater valve.  Remember, if your weeping tiles are connected to the sanitary sewer system you must disconnect the weeping tiles prior to installing a backwater valve.

Useful Tips

If you would like to add a backwater valve to your home, and you have your weeping tiles connected to the sanitary sewer system or storm system, you must first disconnect the weeping tile from the sanitary sewer system and connect the weeping tiles to a sump pit and sump pump prior to getting a backwater valve installed.  Please contact the City to understand if you may qualify for the City of London's Basement Flooding Grant Program

When it is Raining

Check your backwater valve when it is raining outside to see if it is closed.  If it is closed, DO NOT use your plumbing in the house (for example, don't have a shower, don’t do your laundry, don’t flush your toilet, etc.).  This is because if the valve is closed, it prevents water from backing up into your home, BUT it also prevents water from leaving your home too.  Wait until the valve is open again before using any plumbing in the house.

Maintaining My Backwater Valve

Regular cleaning of the backwater valve is the responsibility of the homeowner.  It is recommended you follow the backwater valve manufacturer's guidelines and recommendations for maintenance of your backwater valve.


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