How the valve works
Below the slab, a normally open valve is fitted inline on the building drain. Waste flows out past a hinged flap. If the city sewer surcharges and water starts flowing back, the flap floats up and seals, keeping sewage out of the house.
Routine check
- Find its access lid, a round or square cover set into the slab, often toward the street side of the house.
- Lift it off and shine a light inside. Wear gloves.
- Push the flap gently; it should swing without sticking and its sealing edge should be clean.
- Check the floats, if your model has them, and the clear inspection lid.
- Replace the cover and confirm the seal sits flat.
Cleaning
Follow the maker's instructions. Many models let you lift the flap assembly out for rinsing with a garden hose over a floor drain or utility sink. Do not run water down the house drains while the valve is open.
How often
Look at it at least once a year, typically in spring. Homes with heavy grease use or a history of backups may need more frequent checks.
If you need help
If the flap is stuck or the seal is cracked, our backwater valve page explains repair and replacement options.
Tools worth keeping in the basement
- Two plungers: a flanged one for bowls, a flat cup for basins
- A hand snake around twenty-five feet long
- Adjustable and basin wrenches
- A bucket, rags and a flashlight
- A tag on the main shut-off valve
Ready when you are. One call, a real plumber, an arrival window.
Call now(365) 517-6415