Do You Need a Backwater Valve? A Guide for Durham Region Homeowners
By Pickering Plumbing Team · Published · Updated
What a backwater valve actually does
Every drain in your house, from the kitchen sink to the basement floor drain, flows into one main sewer pipe that leaves your home and connects to the municipal sewer under the street. Normally, everything flows one way: out.
During a heavy storm, the municipal sewer can fill up faster than it drains. When that happens, wastewater can push back up the pipe toward your home and come out of the lowest opening it finds. In most houses, that's the basement floor drain, a basement toilet or a laundry tub.
A backwater valve is a one-way valve installed on your main sewer line. Inside is a flap that stays open so wastewater can leave the house normally. When sewage starts flowing backward, the flap floats up and closes, sealing the line so the backup can't get into your basement.
Which homes benefit most
Not every home needs a backwater valve, but many in Durham Region are good candidates. You should seriously consider one if:
- You've had dirty water come up through a floor drain, even once.
- Your basement is finished, or you plan to finish it. Sewage damage to drywall, flooring and furniture is costly and unpleasant to clean up.
- Your home has plumbing fixtures in the basement, like a bathroom or laundry.
- Neighbours on your street have had sewer backups during storms.
- Your home is in a low-lying area or one of the older neighbourhoods where the sewer system was built decades ago.
If your home has never had a backup and your basement is unfinished and fixture-free, a valve may be lower priority. A plumber can look at your setup and give you an honest opinion.
Types of backwater valves
The type usually recommended for homes is a normally open valve installed in the main sewer line inside the basement. Its flap stays open, so your plumbing drains freely, and it closes only when a backup occurs. Because it sits in the floor with an access cover, it can be inspected and cleaned.
Older or cheaper approaches include small plugs or flaps that fit into the floor drain itself. These protect only that one drain, and a backup can still come up through a basement toilet, shower or laundry tub. A mainline valve protects the whole basement.
Some municipalities have specific requirements for the type and location of backwater valves, and installation typically needs a plumbing permit. Check with the City of Pickering or your local municipality before work starts. A good plumber will handle the permit for you.
What installation involves
Installing a mainline backwater valve is a real construction job, not a quick fix. Here's what usually happens:
- The plumber locates the main sewer line, often with a camera inspection to check its condition and confirm where it runs.
- A section of the basement floor is cut and removed over the pipe.
- The pipe is cut and the valve is installed in line, level and facing the right way.
- The valve is tested, and the area is backfilled and finished with concrete, leaving an access cover at floor level.
- The work is inspected if a permit is required.
If the camera shows problems in the sewer line, like roots, cracks or sagging sections, it's often smart to deal with them at the same time, since the floor is already open.
Our backwater valve installation service includes the camera inspection and an upfront quote before any concrete is cut.
Rebates and subsidies
Several municipalities in Ontario have offered subsidies to help homeowners install backwater valves and other flood protection. Programs change, open and close, and often have conditions such as using a licensed plumber, getting a permit, or applying before the work is done.
Before you book, check with the City of Pickering or the Region of Durham (or your own municipality if you live in Ajax, Whitby or elsewhere) to see what's currently available and what paperwork they need. It's worth also asking your home insurance provider, since some insurers look favourably on flood protection.
Living with a backwater valve
A backwater valve needs a little attention to keep working:
- Keep the access cover clear so you can reach it. Don't build a floor or cabinet over it.
- Inspect it at least once a year and after a major storm. Look for debris that could keep the flap from closing or opening fully.
- Be careful what goes down the drains. Grease, wipes and other debris can foul the flap.
- During a backup, when the valve is closed, avoid using water in the house. Your own wastewater can't leave while the valve is shut, so running the dishwasher or flushing toilets can cause water to back up inside.
If you'd prefer not to do the inspection yourself, we can include it in a regular plumbing check. Pairing a backwater valve with a well-maintained sump pump gives a basement the best protection against both sewer backups and groundwater. Our article on basement flooding in Pickering explains how the two work together.
Next steps
If you're on the fence, start with a camera inspection of your sewer line. It tells you the pipe's condition, where a valve would go, and whether there are any other problems worth knowing about. From there, you can decide with real information instead of guesswork. Homeowners in older lakeside areas like West Shore often find the inspection alone is worth it.
Common questions about backwater valves
Will a backwater valve stop all basement flooding? No. It stops sewage from coming back into your home through the drains. It does nothing about groundwater seeping through the foundation, which is a job for proper grading, eavestroughs and a sump pump. Most basements are best protected with both.
Does a backwater valve slow down my drains? A properly installed, normally open valve shouldn't affect how your drains work day to day. Water flows through it freely. If drains start to slow after installation, the valve may need cleaning or there could be a separate problem in the line.
How long does installation take? For most homes, installing a mainline valve is a one-day job, though drying and finishing the concrete can take longer. Permit and inspection timing depends on your municipality.
Can I install one myself? It's not a do-it-yourself job. It involves cutting the basement floor and the main sewer line, and it usually needs a permit and inspection. A mistake can leave your home unprotected or cause drainage problems, so hire a qualified plumber.
