ResidentialBasements
Fitting a Backwater Valve
When a downpour overloads the city sanitary main, sewage can flow backward into your basement. A backwater valve closes to stop it.
Bright kitchen interior featuring a sleek faucet, sink, and a scenic window view.
- Pit, float, check valve and discharge line all inspected
- Pump cycled with a bucket test, not assumed to work
- Backwater and sump layout explained for your basement
- Advice on City of Markham flood programs (confirm current terms)
- Licensing details confirmed when you call
- Residential
- Commercial
- Markham & York Region
How the job runs
- Homes with a basement floor drain, toilet or shower below street level.
- Houses on streets that have had sewer backups before.
- Anyone finishing or refinishing a basement.
- Insurers increasingly ask about them when you renew.
What's included on this job
What we open
A section of basement floor over the main drain, cut and broken out, then patched with new concrete.
What we bring
Concrete saw, jackhammer, sewer camera, and a mainline backwater valve with access cover.
What we replace
A section of the main drain replaced with the valve body, and new concrete over the access box.
How we prove it
Water run from every fixture to confirm flow, the flap checked, and the access lid left serviceable.
Signs you need this
- Sewage has come up a floor drain before
- The street sewer is older and shared
- A finished basement below street level
- The city has a subsidy programme open
How it protects a Markham basement
During intense rainfall, some of that water enters the sanitary sewer through cracks, manholes and old connections. If the sewer fills faster than it drains, pressure pushes back toward the lowest openings in each house. A normally open backwater valve lets your wastewater flow out but closes with a flap when flow reverses.
How we install it
- We confirm the permit requirements with the City of Markham. Backwater valves usually need a plumbing permit and inspection.
- We locate the main drain in the basement floor, often with a camera.
- We cut and remove a section of slab over the line.
- A normally open valve goes into the drain, set level and reachable.
- We add a cover box so the valve can be inspected and cleaned.
- The city inspector checks it before the floor is patched.
From the van: While the flap is shut in a storm, anything you drain inside the house simply pools at the lowest fixture. Go easy on laundry and showers until the storm passes.
Subsidies
The City of Markham has offered a flood protection subsidy toward a backwater valve installed by a licensed plumber with a permit. Check the current rules and amounts before you book, since programs change.
Care and checks
Lift the inspection lid each spring and again in autumn. Confirm the flap swings and that no debris has caught in the body. A quick rinse keeps it working.
A backwater valve shuts the door on the city sewer. It needs a permit and room to service it.
What changes the cost
Slab thickness, drain depth, finished flooring, and how the line is laid out all matter. Permit and inspection fees are separate.
Call before it gets worse
A sewer backup is one of the most unpleasant cleanups a homeowner can face. Prevention is far cheaper.