What is a Backwater Valve?
A backwater valve (also called a backflow preventer or sewer backup valve) is a one-way valve installed in your home's main sewer line. It allows sewage to flow out from your home normally, but automatically closes if municipal sewage starts flowing backward — preventing it from backing up into your basement floor drain, toilet, or laundry tub.
Why You Need One
During heavy rainstorms or spring snowmelt, municipal sewer systems can become overwhelmed. When the city's combined sewer or sanitary sewer reaches capacity, wastewater can reverse direction and flow back into homes through their own floor drains. The result is raw sewage flooding your basement — one of the most expensive and devastating home emergencies possible.
- Heavy rain events overload municipal combined sewer systems
- Older neighborhoods with combined storm and sanitary sewers are especially vulnerable
- Basement floor drains are the first point of entry for sewer backup
- Damage from sewer backup can cost tens of thousands of dollars to remediate
- Many insurance companies offer premium discounts for homes with backwater valves
Municipal Rebate Programs
The Region of Waterloo and many Ontario municipalities offer rebate programs for backwater valve installation — often covering a significant portion of the installation cost. Ask us about current programs in your area when you call for a quote.
Our Installation Process
Locate the Main Sewer Line
We identify the exact location of your main sewer line as it exits the basement floor — typically near the floor drain or utility area.
Excavate & Access the Pipe
The concrete floor is carefully cut and excavated to access the main sewer pipe at the correct installation point.
Install the Backwater Valve
A code-compliant backwater valve is installed in the main sewer line. The valve flap allows normal flow out, but seals automatically if flow reverses.
Restore the Floor
The excavated area is backfilled and concrete is poured to restore the floor. A cleanout access point is provided above the valve for future maintenance.
Ontario Building Code Requirements
All backwater valve installations must comply with Ontario Building Code requirements and local municipal plumbing codes. Our installations are code-compliant and we can advise on permit requirements in your municipality.
Note: A backwater valve protects against sewer backup but is not designed to address groundwater or foundation water issues. If you have both concerns, we can combine solutions for complete basement flood protection.