Protect your foundation through our backwater valve installation service. We install heavy-duty backwater valves to permanently block reverse wastewater flow into your drains. Free expert estimates. 25-year warranty.
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Most homeowners do not think about their sanitary drain until raw sewage comes through the floor drain. Then they think about nothing else. A single sewer surcharge event during a storm pushes hundreds of gallons of contaminated water into any basement without a backwater valve installed.
At DrainCom, we install, repair and service backwater valves daily. We assess your drain layout, specify the correct valve type, complete the plumbing connection to code and test the mechanism before we leave. We also manage your rebate application from start to finish so you recover every dollar available.
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Every backwater valve installation we complete is sized and positioned to your specific drain configuration. We do not offer a standard installation applied to every property.
The mainline position, directly on the primary sanitary lateral, is the most effective location for a drain backwater valve. It protects every connected fixture simultaneously: floor drains, toilets, laundry tubs and below-grade showers. One valve. Complete lateral protection.
We open the basement floor at the access point, cut into the lateral and fit a code-compliant backwater valve with an inspection chamber visible at floor level. The chamber must remain permanently accessible, as the Ontario plumbing code and most municipal rebate programs require annual inspection.
Where the mainline lateral runs deep or access from inside the basement is restricted, sewer backwater valve installation is completed through exterior excavation of the lateral. We assess access conditions during the free inspection and advise on the correct approach before any work is quoted.
Either approach qualifies for city and regional flood prevention rebates. We confirm your eligibility and manage the application process as part of the installation.
Backwater valve plumbing must match the existing lateral material, whether PVC, ABS, cast iron or clay, and must be installed in the correct flow direction with adequate slope. An incorrectly oriented drain backwater valve will fail to seal during a backflow event or will obstruct normal drainage.
We do not use generic fittings or apply standard approaches across different drain configurations. The specification is matched to what is actually in your property.
Floats jam. Seals deteriorate. Flap hinges corrode. Debris accumulates in the chamber. A backwater valve with any of these failure modes will not close when a sewer surcharges. We diagnose and repair on-site where the component is serviceable, or replace the full valve where it has reached the end of its service life.
Annual backwater valve maintenance is a requirement under most municipal rebate programs and a recommendation under the Ontario plumbing code. Our service includes removing the access cover, clearing chamber sediment and debris, cycling the flap or float mechanism through a full test, verifying the seal and confirming the chamber is accessible to the correct height.
A valve that has not been serviced in multiple years frequently jams open from grease accumulation. It looks installed. It provides no protection.
A backwater valve stops sewer backflow. A sump pump manages groundwater and surface drainage. They address entirely different water entry pathways. Properties in flood-risk zones need both. Combined installation qualifies for stacked rebates in Peel Region: up to $1,500 for the valve and up to $6,000 for the sump pump in the same project.
Installation cost depends on whether access is from inside the basement floor or through exterior lateral excavation, the depth and condition of the existing drain pipe and the valve type required by your drain configuration.
| Service | Price Range (CAD) | Notes |
| Backwater valve (inside installation) | $2,200 to $2,700 | Interior access through the basement floor |
| Backwater valve (outside installation) | $2,400 to $3,500 | Exterior excavation; full lateral access |
| Backwater valve repair | $300 to $800 | Float, seal or housing replacement |
| Backwater valve maintenance and inspection | $150 to $300 | Annual service recommended |
| Sewer backwater valve with sump pump (combined) | $4,000 to $6,500 | Full flood protection package |
Written quotes are provided after a free on-site inspection. No change orders once work starts.
Every major municipality in the region offers rebates for licensed backwater valve installation. Here is the current breakdown:
| Municipality | Qualifying Installation | Maximum Rebate (CAD) |
| Mississauga / Peel Region | Backwater Valve on Storm Lateral | Up to $1,500 |
| Sump Pump (combined install) | Up to $6,000 additional | |
| City of Toronto | New Backwater Valve on Main Sanitary Drain | $1,250 |
| Pipe Severance and Capping | $400 | |
| City of Vaughan | Backwater Valve Installation | $750 |
| Durham Region | Backwater Valve or Sump Pump | $3,000 interest-free 3-yr loan |
| Burlington / Halton Region | Backwater Valve Installation | Contact us to confirm the current program |
Peel Region homeowners installing a backwater valve and sump pump in the same project qualify for combined rebates of up to $7,500. We manage all documentation and submissions.
One call covers everything: We handle the permit, the installation, the inspection documentation and the rebate application. You do not need to navigate three separate processes.
A backwater valve is a one-way mechanical gate installed on the sanitary drain lateral where your home connects to the municipal sewer system. Under normal conditions, the valve sits open and waste drains freely. When the municipal system surcharges and flow attempts to reverse, the mechanism closes automatically and holds. Sewage stops at the valve. If you have already experienced a backup, immediate professional flood basement cleanup in the GTA is critical to safely restore your home.
To install a backwater prevention valve, the lateral must be accessible either through the basement slab or by excavating outside. The valve requires a permanent inspection chamber at floor level with a removable cover. This is not optional. Ontario Building Code requires the chamber to remain unobstructed and accessible at all times for annual inspection.
The valve does not require electricity or manual operation. It responds entirely to flow direction. When the surcharge passes and municipal pressure normalizes, the valve opens again and normal drainage resumes.
Critical distinction: A backwater valve stops sewage from entering the home. It does not stop groundwater. It does not manage surface flooding. It does not prevent a sump pump from overflowing. Each of those requires a different device. We assess which combination your property needs.
Sewer surcharge events are more frequent than they were two decades ago. The infrastructure was not built for the current storm intensity or population density. When intensity exceeds capacity, sewage travels the path of least resistance, which is backwards through residential laterals into unprotected basements.
storm and sanitary drainage share a single pipe in many older areas. During heavy rain, storm volume overwhelms the pipe. The entire system backs up, and sewage reverses into any home without a valve
a blockage in the municipal main or in the portion of your lateral beyond your property line creates immediate backpressure. Your home has nowhere to drain. It reverses
tree roots penetrating the sanitary lateral constrict the flow. Under storm load, partial blockages escalate into full backflow events
older clay and cast iron laterals shift, crack and compress over decades, restricting flow to the point where ordinary household drainage creates backpressure
a historical practice that contributes to sewer surcharge when pumps run continuously during storm events
None of these conditions is within the homeowner's control. The municipal system will surcharge again. The only variable is whether your home has a mechanical barrier.
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This is not a scare tactic. These are the real costs that homeowners who call us after a sewage backup have paid.
Every homeowner we speak to after a sewage backup asks us the same question: why did nobody tell me how cheap the valve was before this happened?
Four to six hours from start to tested completion. Concrete is cut, the valve is installed and plumbed, and the opening is closed with new concrete. Curing requires 24 hours before the access cover is finalized.
One full day. Excavation, valve installation, backfilling and surface restoration.
One to two days, depending on whether a new sump pit is required.
Most homeowners remain in the property throughout the installation. There is no need to vacate. Plumbing use is restricted during the installation window only, typically two to three hours while the lateral connection is open.
Business Hour:
Monday to Friday: 8a.m -9p.m
Saturday and Sunday: 9a.m – 2p.m
Look for a small rectangular or circular access cover set into your basement floor, usually within two to three feet of the main floor drain or near where the drain exits the house. The cover is typically plastic or metal and can be lifted. Inside, you will see the valve chamber. If you cannot find one, or if you are not sure what you are looking at, call us. We will confirm during the free inspection.
No. Each property has its own sanitary lateral connecting to the municipal main. Your neighbour’s valve protects only their lateral. Sewage reversing through the municipal main will still enter your lateral and your home if your property has no valve installed.
Technically, yes, but you should not. When the valve seals during a surcharge event, wastewater from inside the home has nowhere to go. Flushing a toilet or draining a sink forces water to back up into the basement through the lowest open drain. If the valve has closed, it means the municipal sewer is surcharging. Limit plumbing use to what is essential until the storm passes and the valve reopens.
The Ontario Building Code requires a normally-open backwater valve on the sanitary drain lateral. Acceptable types include flap valves, float valves and swing-check valves, provided they are CSA-certified and installed with a permanently accessible inspection chamber. The specific type we install is determined by your drain configuration, depth and pipe diameter. We confirm the specification during the inspection.
Under normal conditions, no. The valve floats fully open during regular drainage and offers virtually no resistance to flow. Homeowners with properly installed valves report no change in drain performance. The only time the valve affects plumbing use is when it seals during a surcharge event, which is exactly when it is supposed to.
It is never too late, but the sequence matters. The sewage contamination must be professionally remediated first. Installing a waterproofing or flood protection system over a space with active sewage contamination traps the biological hazard inside the structure. Once the remediation is complete and the space has passed clearance testing, we install the valve, and you are protected going forward.
An interior backwater valve installed below the basement floor is in a conditioned or semi-conditioned environment and is not at freeze risk. Exterior valves installed in unheated areas carry some freeze exposure. We specify installation depth and insulation to eliminate freeze risk on every exterior installation. This is assessed as part of the site inspection.
In most municipalities, yes. A plumbing permit is required for work that involves cutting into the sanitary lateral. We obtain the required permits as part of the installation process. Permit documentation is also required for most city rebate applications. Homeowner-installed valves are ineligible for all rebate programs across the region.
905-238-6800