One heavy storm can push city sewage back up your floor drain. A sewer backflow valve stops it at the foundation wall. We install, inspect, and maintain backwater valves across Scarborough — permit, City inspection, and paperwork for the Toronto basement flooding subsidy of up to $1,600 all handled for you.
When a summer storm overloads Scarborough's combined and sanitary sewers — as it did across Agincourt, Wexford, and Clairlea in the July 2024 floods — the water has nowhere to go but back up the lateral into the lowest drain in the house: your basement floor drain, shower, or laundry tub. A backwater valve is a one-way gate installed on the main sewer line just inside the foundation. Sewage flows out normally; when the city sewer surcharges, a flap closes and nothing comes back in.
At ASAP Scarborough Plumbing Services, we install, inspect, and maintain backwater valves across Scarborough as a City-licensed contractor — which matters, because that licence is a condition of the City of Toronto's basement flooding subsidy. One important distinction: this is a sewer backflow valve for wastewater. It is not a backflow preventer, which protects your drinking water supply from contamination and is a separate device, a separate inspection regime, and a separate service.
Had water come up the floor drain once already? Call (437) 475-2458 — a backwater valve is the single most effective basement flooding prevention device for a Scarborough home, and the City pays up to 80% of it.
Any home with a finished basement and a floor drain is a candidate. These are the properties where we see sewer backup most often:
Homes at the bottom of a street grade in Wexford, Clairlea, Ionview, and Kennedy Park sit lowest on the sewer run and take the surcharge first. Many are in the City's designated basement flooding study areas.
If sewage has come up the floor drain even once, it will again. Insurers increasingly ask whether a backwater valve is installed before renewing sewer backup coverage.
In Malvern, Milliken, and Agincourt townhomes with a rental suite downstairs, one backup means weeks of lost rent on top of the cleanup. A valve plus a sump pump is the standard protection package.
Scarborough is part of the City of Toronto, so every eligible home qualifies for the Basement Flooding Protection Subsidy Program. The amounts below apply to work completed on or after November 12, 2025.
Confirm eligibilityWe check the property type, downspout status, and whether a valve is feasible on your lateral before quoting.
Permit & installWe pull the building permit, install the valve, and book the City inspection with the floor still open.
Your paperwork packItemized, paid-in-full electronic invoice with our licence number, property address, completion date, the permit, and photos of the installed valve.
Submit onlineYou file through the City's subsidy portal. Funding is first-come, first-served, so we recommend applying the week the inspection passes.
Not sure if your home qualifies? We'll tell you on the first call.
(437) 475-2458Most Scarborough installs take one working day. Here's what actually happens in your basement:
Locate the lateral and pull the permit. We camera the main drain to find where it leaves the house, confirm there's no existing valve or trap in the way, and file the building permit.
Open the floor. A section of concrete roughly 60 × 120 cm is cut near the foundation wall. Finished flooring in that strip is removed; we tarp and contain the dust.
Install the valve with an access box. The pipe is cut, the normally-open valve is set on the correct slope, and an access cover is placed flush with the floor so the valve can be serviced later.
City inspection, then close up. The inspector verifies the valve before we backfill and pour new concrete. The access lid stays visible — that's what you'll open for maintenance.
One job, one visit, inspection included — and a valve that stays serviceable for the life of the house.
A valve only works if the flap can close. Once a year — ideally before the spring thaw — it needs to be opened, cleaned, and tested. And it protects against only one of the three ways water gets into a Scarborough basement.
We lift the access lid, remove the gate, clear grease and debris from the seat, check the O-ring and hinge, and confirm the flap swings freely and seals. Fifteen minutes that keeps your subsidy-funded valve actually working.
The valve stops sewer backup; it does nothing for water rising through the weeping tile. A sump pump with battery backup handles that — and the City subsidizes it on the same application, up to $2,250 plus $300 for the backup.
Roof water piped into the sewer is what surcharges it in the first place. Disconnecting downspouts is mandatory in Toronto and a condition of the subsidy. We extend them to drain safely away from the foundation while we're on site.
Valve, pump, and downspouts in one visit — one quote, one subsidy claim.
(437) 475-2458A backwater valve is a one-way gate fitted on the main sewer line where it leaves your basement. In normal use the flap sits open and wastewater flows out to the city sewer. When a storm surcharges the sewer and water tries to push back toward the house, the flap closes against the flow and nothing comes up your floor drain. It's a mechanical device with no power needed, which is why it's the first thing Toronto recommends for basement flooding prevention.
No — a backwater valve and a backflow preventer are different devices for different pipes. A backwater valve goes on the sewer drain and keeps sewage out of your basement. A backflow preventer goes on the water supply and keeps contaminated water from flowing back into the drinking water system; it's usually required on commercial properties and irrigation systems and has its own annual testing rules. This page is about sewer backwater valves. If you need a backflow preventer, tell us when you call and we'll quote that separately.
The backwater valve subsidy in Scarborough comes from the City of Toronto's Basement Flooding Protection Subsidy Program: 80% of the invoiced cost up to $1,600 per valve, for up to two valves, on work completed on or after November 12, 2025. A sump pump on the same application is covered up to $2,250 plus $300 for a battery backup, with a lifetime cap of $6,650 per property. You need a building permit, a City inspection before the floor is closed, a contractor with a Toronto business licence, and disconnected downspouts. We provide the permit, inspection, and invoice package; you submit online within two years.
Yes to both. A building permit is required for backwater valve installation in Toronto, and the City must inspect the valve before it's covered — skip either and you lose the subsidy. Installing the valve means cutting a section of the concrete floor near the foundation wall, roughly 60 by 120 centimetres, to reach the sewer line. We contain the dust, pour new concrete after the inspection, and leave a flush access lid so the valve can be serviced without opening the floor again.
A backwater valve needs maintenance once a year, and the best time is early spring before the thaw and the first big storms. Grease, wipes, and debris collect on the gate and can stop it from closing fully — which means the valve is there but not protecting you. We open the access box, remove and clean the gate, check the seal, and test the flap. Many Scarborough customers book it alongside their annual sump pump test.
Usually yes — a backwater valve and a sump pump solve two different problems. The valve blocks sewage coming back up the drain; the pump removes groundwater that seeps in through the weeping tile and foundation. In a heavy storm both happen at once. The City subsidizes both on the same application for that reason. If you're not sure whether your home needs the pump, our sump pump team can assess it on the same visit.
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"Sewage came up our Wexford floor drain in the July storm. ASAP installed a backwater valve, handled the permit and the City inspection, and gave us the invoice package for the subsidy. Got $1,600 back."
Gary M.
2026-01-20
"Searched backwater valve installation near me after our insurer asked about one. ASAP explained the difference from a backflow preventer, quoted upfront, and did the whole job in a day in our Clairlea bungalow."
Preethi R.
2026-02-11
"Valve and sump pump with battery backup in one visit at our Agincourt house. They disconnected the downspouts too so we'd qualify. One application, most of it covered by the City."
Steven L.
2026-03-05
"Annual maintenance on the valve the previous owner installed in our Guildwood home. Gate was half-blocked with grease — would not have closed. Glad we booked it before spring."
Monica T.
2026-04-02
"Basement apartment in our Malvern townhouse flooded twice. ASAP installed the sewer backflow valve, poured the floor back clean, and the tenant never noticed anything but the access lid."
Hassan A.
2026-05-14
"They camera'd the line first and found our Kennedy Park house still had an old building trap that had to come out before the valve could go in. Explained it, quoted it, done. No surprises."
Linda F.
2026-06-23
"Looked up plumber near me for a backwater valve in Birch Cliff. Inspector passed it first time, and the dust containment was better than the reno crew we'd had in before."
Derek W.
2026-08-18
"Booked a fall valve check and sump test for our West Hill place before the wet season. In and out in half an hour, both working. Easy peace of mind."
Nadia S.
2026-10-07