Backwater Valves
A normally open valve on the sanitary or storm drain that closes when the sewer backs up, installed under a City permit as part of a flood plan.
Interior retrofit about $1,500–$4,500 (published Ontario contractor pricing, 2025–26; yours will differ). We found one source only for an outdoor valve, so no range is shown for it.
Find a Waterproofing ContractorAbout Backwater Valves
A backwater valve sits on the building drain and is meant to close during a sewer surcharge, when the sewer backs up toward the house. The Building Code allows one in a building drain only if it is of a "normally open" design and serves no more than one dwelling unit (O. Reg. 163/24, 7.4.6.4). The City requires backwater valves on the sanitary laterals of all new single, semi-detached, row house and townhome units.
The City says a building permit is required to install protective plumbing devices; the plumbing-only permit fee is $117 per application on the 2026 schedule. Plumber is a compulsory trade in Ontario, so ask who does the plumbing work.
A valve protects against sewer backup, not seepage. The City's own FAQ lists what protective plumbing will not stop: water through cracks in walls or window wells, failed foundation drains or sump pumps, overflowing eaves and plugged downspouts, poor foundation or lot drainage.
City rebate (Residential Protective Plumbing Program): indoor sanitary valve up to $1,000 (home built before 2012); storm valve up to $1,000 and outdoor storm valve up to $2,500 (home built before 2004); plus 100 per cent of the plumbing permit fee. The City rebates the lesser of the maximum or the cost, within 18 months of the permit's issue date, and lists the program as currently under review: check ottawa.ca before you rely on it (checked September 2026).
Published Ontario prices for an interior retrofit: about $1,500 to $4,500.
What This Work Covers
- Normally open valve, one dwelling unit
- Building permit ($117 plumbing-only fee on the 2026 schedule)
- Licensed plumber for the plumbing work
- Access for inspection and maintenance
- Rebate paperwork: permit, inspection report, paid itemized invoice
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What this work costs
Common questions about backwater valves
- Does a backwater valve need a clean-out access in an Orleans basement?
- Who maintains a backwater valve in an Ottawa home?
- Does an outdoor backwater valve have a published price in Ontario?
- Should a backwater valve be part of a basement waterproofing plan in Ottawa?
- Does the 18-month rule start from the permit in Ottawa's rebate program?
- Is my Barrhaven house too new for the storm backwater valve rebate?
- How much does a City permit add to a sump pit job in Vanier?
- What plans does the City of Ottawa want for a sump pump permit?
Other Waterproofing Services
Exterior Foundation Waterproofing
Digging down the outside of the foundation to the footing and putting a membrane or coating on the wall, with new drain tile at the bottom where it is replaced.
Interior Drainage & Sump Systems
A drain channel cut in along the inside of the basement floor that carries seepage to a sump pit and pump, without digging outside.
Weeping Tile Replacement
Replacing the drain pipe at the base of the foundation that collects groundwater, laid to the Building Code's size and stone rules.
Foundation Crack Injection
Sealing a leaking crack in a poured concrete foundation from the inside by injecting it, priced per crack.
Sump Pumps & Battery Backup
New sump pits, pump replacement and battery backup pumps, with the City permit and the protective plumbing rebate in view.
Window Wells
New or replacement basement window wells, drained to the footing as the Building Code requires.
Structural Foundation Repair
Repairs to a foundation wall or footing that carries load, which the City lists as building permit work.
Ready to Get Started?
Tell us about your backwater valves job and we'll send it to local waterproofing contractors in Ottawa. They reply by email.