Plumbing service
Backwater valve installation
In a cloudburst the city sewer may fill faster than it empties, and the pressure pushes water back up the lowest drains. A backwater valve on your main line closes when that happens.
- Where it goes: On the house drain in the basement, past every fixtures
- Valve type: Normally open with a flap that closes on reverse flow
- Permit: Required in Toronto
- Subsidy: Toronto has put money toward basement flood protection in past years; ask what applies today
- Licensed, insured trade work (details confirmed when you call)
- Diagnosis before anything is cut
- Emergency calls taken
- Etobicoke and the west end
At a glance
- Where it goes
- On the house drain in the basement, past every fixtures
- Valve type
- Normally open with a flap that closes on reverse flow
- Permit
- Required in Toronto
- Subsidy
- Toronto has put money toward basement flood protection in past years; ask what applies today
How the valve protects you
A normally open backwater valve lets sewage leave the house freely. When water tries to flow back from the street, a flap floats up and seals. That keeps sewer surcharge out of the floor drain, the basement toilet and the laundry tub.
- The trade-off is that while the valve is closed, water you send down the drains is stuck behind the flap.
- In a heavy downpour, holding off on laundry and long showers is part of using it properly.
Installing it right
We cut the basement floor along the main drain, remove the section of pipe, and bed the valve dead level under a removable access lid so the flap can be inspected. The placement matters: the valve must protect every basement fixture but should not block foundation drains that rely on gravity, which can push water against the walls.
- Toronto requires a plumbing permit for this work, and the city has offered a subsidy towards the cost for eligible homeowners.
- Check the City of Toronto website for current eligibility before booking.
Looking after it
The valve needs an occasional check: open the cover, make sure nothing is caught under the flap, and confirm it moves freely. We walk you through it the day it goes in.
- Combined with a sump pit fed by the disconnected weeping tile, a backwater valve is the most effective protection most Etobicoke basements can get.
Signs to watch for
- Basement has flooded during a storm before
- Street has a history of sewer backups
- Finishing the basement soon
- Floor drain gurgles during heavy rain
- Neighbours have installed valves recently
How the job runs
Camera the main
We confirm the pipe route and condition first.
Permit and cut
A permit is pulled, then the slab is opened over the main.
Set the valve
The valve is installed level with an access cover.
Inspect and restore
After inspection the floor is patched.