Backwater Valve Installation

How a backwater valve works

A mainline backwater valve is installed on the house's primary drain, below the basement floor, close to where the pipe leaves the house. Inside sits a flap that hangs open for normal flow out to the street. If sewage starts heading back toward the house, the flap swings shut and holds. A clear access cover at floor level lets you inspect and clean it.

Installation steps

1. Locate the main drain with a camera and transmitter.
2. Cut and remove a section of basement floor slab over the pipe.
3. Excavate to the pipe, cut in the valve body and couple it to the existing drain.
4. Set the access riser to finished floor height.
5. Backfill, compact and pour new concrete.

In a finished basement, flooring and sometimes a wall section near the cleanout have to come up first.

Permits and inspection

Installing a backwater valve changes the building drain, so a plumbing permit is generally required in Aurora and an inspector checks the work before the floor is closed. We handle the permit and booking. Keep the permit paperwork; insurers often ask for proof that a valve was installed properly.

The valve must be placed so it protects the fixtures it needs to protect. Fixtures upstairs drain normally, but while the valve is closed, nothing in the house can drain out. That is why we tell you to limit water use whenever the valve may be closed during a storm.

Subsidy programs: check current terms

Various municipalities in York Region have offered rebates for backwater valve and sump installations over the years, and some insurers offer premium reductions. Program details, eligibility and amounts change, so check the Town of Aurora and your insurer for current terms before you book. We can provide the documentation most programs ask for.

Looking after it

Lift the cover a couple of times each year, check that the flap moves without catching, and clear any debris from the seat.