Loading page…
Skip to content
City of TorontoMetro master licence15791Request service

Backwater valve installation

A backwater valve stops sewer water from flowing back into your basement when the City sewer is overloaded in a heavy storm. If your basement has flooded through the floor drain before, this is the job to ask about.

Call (416) 489-0000Request service
City of TorontoLicensed & insuredMetro master plumbing licence15791
1212 The Queensway, Etobicoke

A backwater valve is worth a look if

  • Water or sewage has come up your floor drain during a storm
  • Your street or neighbours have had basement flooding
  • You have a finished basement or a basement apartment
  • You are already having sewer work done
  • Your insurer asked about flood protection
Basement floor opened up for drain work, with the Waterworks plumber on site

What a backwater valve does

Your house drain normally flows one way, out to the City sewer. In a heavy storm, the sewer can fill up and push water back toward your house. A backwater valve has a flap that closes when water flows the wrong way, so it cannot come up your basement drains.

The valve goes into the main drain line, usually in the basement floor. That means opening the floor, installing the valve with an access cover, and closing it up so you can still reach the valve to check and clean it.

What to know before you book

  • A permit is needed. Toronto requires a building permit and an inspection before the valve is covered up, and the subsidy depends on it.
  • Some fixtures may be cut off during a storm. While the valve is closed, water you use in the house cannot drain out. Go easy on water during a heavy storm.
  • It needs a quick check now and then. Debris can keep the flap from closing. We show you how to look.
  • It works best with downspouts disconnected from the sewer. The Toronto subsidy requires that too, or an exemption.

Financing through Financeit

Financing is available through Financeit for eligible residential projects. Ask Waterworks about the options for your job. Financing is subject to credit approval. Terms and conditions apply.

Photos from our work

Real project views and work stages supplied by Waterworks. Swipe through the album or open any photo.

01 / 10

Photo 1 of 10
Underfloor pipework during an installation.

Underfloor pipework during an installation.

See the work

Watch Michael on the job

Angelo on his backflow prevention work
A sewer backup in a Toronto basement

A customer review

“Michael from Waterworks quickly diagnosed what was behind our recent basement drain backups. Within a few days everything was taken care of…”

Patrick, Toronto. 5 out of 5 on HomeStars, August 8, 2026.

Questions people ask

Request service

Tell us what is happening and we will call you back to book. For leaks and backups, calling is faster.

(416) 489-0000
Evenings and weekends
Phones answered. Overnight calls booked first thing in the morning.
Office
1212 The Queensway, Etobicoke, ON M8Z 1R8

For example M8Z 1R8 or Mimico

How urgent is it?

We only use this to reply about your job. See our privacy page.

Plumbing help for your home.(416) 489-0000Request

Residential plumbing & drains

Let’s get your home sorted.

Tell us what’s happening. We’ll call you to arrange a visit.

For example M8Z 1R8 or Mimico

How urgent is it?

We only use this to reply about your job. See our privacy page.