The basics
Buried in the main sewer line below your slab is the backwater valve, with a removable cover at floor level. Within it hangs a flap that rests open while you use water and swings shut when the sewer pushes back. Debris, grease or a stuck float can stop it from closing, which defeats its purpose.
- Find the access cover, most often a short way in from the street-side wall
- Keep it clear of boxes, furniture and flooring
- Know that while it is closed, water you use has nowhere to go
Step by step
- Wear gloves. This is a sewer line.
- Remove the cover. Most unscrew or unclip by hand.
- Look at the flap. It should sit open and move freely when gently lifted.
- Clear debris. Remove anything caught on the flap or seat, using a brush and a little water.
- Check the seal. Make sure the cover gasket is intact before replacing it.
- Replace the cover firmly. A loose cover can leak if the valve closes.
Time to bring in the shop
Call us if the flap is damaged, will not move, or if water seeps from the access cover. Also call if the valve was installed without a proper cleanout or if fixtures downstream of it are not protected. If you do not yet have a valve, our installation page explains the process, and the subsidy guide covers possible support from the Region.
During a storm
If heavy rain is forecast and your area has had backups before, limit water use until the storm passes. Laundry and dishwashing can wait a few hours.
Asked at the shop counter
How regularly does the valve need a look?
Spring and fall, plus once after every serious downpour.
Why does water come up around the cover?
The seal may be worn or the cover loose. Replace the gasket or call us.
Can I flush toilets when the valve is closed?
Avoid it. Water has nowhere to go until the valve reopens.
Questions about this job? Call (365) 413-9125 and talk to a plumber.