Code-compliant placement
Installed inside the dwelling and left accessible, per the Ontario Building Code.
What a Backwater Valve Does
A backwater valve sits on the sanitary line inside the house and closes automatically if sewage tries to flow backward into the home during a surcharge in the municipal system – typically during heavy rain when the City's sewer system is under extra load. Without one, that backup has nowhere to go but up through the lowest drains in the house, most often a basement floor drain or shower.
Ottawa's Backwater Valve Rules
Mandatory on New Construction
Required on the sanitary line for homes built after 2012, storm line after 2004.
Permit & Inspection Required
Every installation needs a City building permit and inspection, new build or retrofit.
Must Stay Accessible
Code requires the valve inside the dwelling and accessible for future maintenance.
If your home was built before those cutoff dates, a valve isn't mandatory, but the City's Residential Protective Plumbing Program currently rebates up to $2,500 for an exterior storm backwater valve or $1,000 for an interior sanitary valve, plus the full building permit fee, for a new installation (not a replacement). The application needs to be submitted within 12 months of the permit date – we can flag whether your property looks eligible before work starts, with final confirmation always through the City's own program.
What Happens During Installation
Site Assessment
Locating the sanitary line and the best accessible point inside the dwelling.
Permit Application
Filing the required City building permit before work starts.
Slab Cutting & Inspection
Cutting the slab to reach the line, then a City inspection to close the permit.
Why Ottawa Plumbing Experts for Backwater Valves
Permit & inspection handled
We pull the required permit and coordinate the inspection.
Rebate guidance
We'll flag if your property looks eligible for the City's rebate before work starts.
Backwater Valve FAQs
Is a backwater valve required by law in Ottawa?
Only for new construction – sanitary valves for homes built after January 1, 2012, and storm valves for homes built after January 1, 2004. Older homes aren't required to have one but may still benefit from installing one.
How much is the City's backwater valve rebate?
Currently up to $2,500 for an exterior storm valve or $1,000 for an interior sanitary valve, plus the building permit fee, for a new installation. Confirm current amounts and eligibility with the City directly.
Do I need a permit to install a backwater valve?
Yes, every installation requires a City building permit and inspection.
Where does the valve get installed?
Inside the dwelling, on the sanitary line, in a location that stays accessible for inspection and future maintenance – it can't be buried behind a finished wall.