A sudden spate of rainy weather can flood streets and neighbourhoods. However, flooding can also leave unprepared homeowners facing a foul-smelling menace. In a worst-case scenario, you might face basement flooding from sewage overflow!

To avoid potentially facing stiff repair costs on your own, you should make sure your home has a backwater valve. A sewer backup valve isn’t something that every house has, however.

If you’re unsure, we can help. Read on for a guide on backwater valves and how to see if you have one.

What Is a Backwater Valve And What Does it Do?

backwater valve is a backflow prevention device meant to prevent basement flooding.

A backwater valve allows water to drain from a house while preventing wastewater from coming back up your pipes.

Backwater valves activate when your municipal sewers can’t handle any more waste. For example, this keeps sewage from being pushed back through your fixtures in a flooding scenario.

Inside the valve is a “flap” that allows draining water to flow freely. If water comes from the opposite direction, this flap is pushed close. The flap will re-open once the water recedes.

Where To Look For a Backwater Valve

A sewer backup valve will typically be housed in your basement, close to your sewer line. Older homes are less likely to have one. Newer homes may have been built with one or retrofitted with one. It is generally a good idea to check regardless of your home’s age.

In your basement, you can start searching for the valve near your sump pump. It will usually be close by.

If your basement is cluttered, you may need to move things around. If you happen to find your valve beneath clutter, consider reorganizing your basement.

Covering your backwater valve makes it difficult to check water levels. Additionally, it makes maintenance more time-consuming.

The backwater valve will typically be mounted into the floor. Usually, it has a clear plastic case so you can see inside. If it is opaque, you may remove the cap to peer inside (though exercise caution in doing so).

If you notice water flowing freely, your flap is down and allowing water to drain. If the compartment appears to be filling or is full, the flap has activated. It isn’t recommended to open the cap in this case.

Do I Need a Backwater Valve If I Don’t Have One?

It is generally recommended that you have a backwater valve if you are a homeowner. Not only are backwater valves useful in stopping flooding, but insurance companies also tend to view your home as less of a risk with one.

In municipalities where flooding is more common, you may find that your insurer requires you to have a backwater valve. Some municipal governments offer rebates for having them installed, however.

Lacking a backwater valve can cause damage to the structure of your home over time.

If your basement is consistently damp and has crack-filled walls, you may need a backwater valve. Consistent flooding and moisture can cause mould and mildew that can damage your home.

There are other signs that you may need a sewer backup valve as well.

If you need a backwater valve, it is best to find a plumber to assist. Retrofitting existing plumbing is a tricky procedure that is best left to professionals.

The risks of an improper backwater valve installation are reasonably high. From flooding to wastewater contamination, it’s just not worth it!

Basic Backwater Valve Maintenance

Having a backwater valve installed may require professional assistance, but luckily, maintaining one is an easy DIY job.

Regular DIY maintenance can ensure that your backwater valve functions properly and will reduce the frequency of clogs and breakdowns.

Before conducting any maintenance, make sure to don protective gear! Wastewater is chock full of contaminants that can make you very ill. Gloves and eyewear are a must, but a face mask is also recommended.


Try running hot soapy water down a drain to help clean your plumbing lines a bit before you start working. Alternatively, you can flush the valve itself with water.

Open the cap and inspect the interior of the chamber for obstructions.

If there is any debris or buildup, take care to remove it, so it does not accumulate. This is especially vital around the flap, as it can become stuck and won’t deploy in a flood. Use a brush to scrub the chamber clear of any sewage buildup; you may need to remove debris with your hands.

Make sure to periodically inspect replaceable components such as the floats on the flap or o-rings sealing pipes.

Of course, prevention is the best method when it comes to maintenance.

Pay close attention to what goes down your pipes. Thicker materials such as paper towels can clog your lines and interfere with a backwater valve. Even “toilet safe” wipes may occasionally build up in a valve.

Ensure to inspect the valve to check for any debris periodically. If you find it consistently, you may need to stop using that product.

As with any plumbing issue, remember that there is only so much you can do before consulting a plumber. Your home’s pipes and fixtures are delicate and improper maintenance can be costly!

Need A Backwater Valve Installed?

A backwater valve is a vital piece of plumbing that can prevent backup problems. Without one, your home risks a foul basement flood!

If you’re in the Toronto area, CarbonePlumbing can get your house the sewer backup valve it needs. Locally owned and licensed, we know our neighbourhood and its needs well. We can even work with you to get a rebate on installation!

The post How To Tell if You Have a Backwater Valve first appeared on CarbonePlumbing Blog.