Backwater Valve Cost in Ottawa, and What the City Rebates
$1,500 to $4,500 for an interior retrofit
In published Ontario contractor pricing, 2025–26. We found only one source for an outdoor valve, so no range is shown for it.
A backwater valve is meant to close during a sewer surcharge. It does not stop water through cracks or window wells, so it belongs in a flood plan alongside, not instead of, waterproofing.
Last reviewed 2026-10-01. Published figures, not quotes; yours will differ.
Which job?
| Item | Published range |
|---|---|
| Interior retrofit | $1,500 to $4,500 |
What the quote should say
- Which drain the valve goes on (sanitary or storm)
- A normally open valve serving one dwelling unit (7.4.6.4)
- Where it sits, and how it can be reached for inspection and maintenance
- Who pulls the building permit and books the inspection (the City's backwater valve page asks for 48 hours' notice)
- Whether a licensed plumber does or signs off the plumbing part
Permits
The City of Ottawa says a building permit is required to install protective plumbing devices, which include backwater valves; the plumbing-only fee is $117 per application on the 2026 schedule. The City's backwater valve page says the valve must be located within the dwelling unit and accessible for inspection and maintenance, and asks for inspections to be booked 48 hours in advance.
City rebate
The City of Ottawa's Residential Protective Plumbing Program lists these maximums for this kind of work. They are shown on their own and are not taken off any price above.
| Item | City maximum |
|---|---|
| Indoor sanitary backwater valve (home built before January 1, 2012) | $1,000 |
| Storm backwater valve (home built before January 1, 2004) | $1,000 |
| Outdoor storm backwater valve (home built before January 1, 2004) | $2,500 |
| Building permit (plumbing work only) | 100 per cent of the current fee |
- The City rebates the lesser of the maximum or the cost of the work.
- The work must be complete and the application received within 18 months of the building permit's issue date (the City changed this from 12 months on July 1, 2026).
- Rebates are not available for maintenance, repair or replacement of existing protective plumbing devices, or for devices the City installed.
- The City lists the program as currently under review: check ottawa.ca before you rely on it (checked September 2026).
Waterproofing IQ answers on this job
- Does an outdoor backwater valve have a published price in Ontario?
- Should a backwater valve be part of a basement waterproofing plan in Ottawa?
- Is my Barrhaven house too new for the storm backwater valve rebate?
- Who maintains a backwater valve in an Ottawa home?
- Does a backwater valve need a clean-out access in an Orleans basement?
Quick answers
Will a backwater valve stop water through the walls?
No. The City's protective plumbing FAQ says these devices will not stop water through cracks in walls or window wells, failed foundation drains or sump pumps, overflowing eaves troughs and plugged downspouts, poor foundation or lot drainage, or water sources inside the house.
Who maintains the valve?
The City says the owner maintains protective plumbing devices to the manufacturer's directions.
Want this done at your place?
Tell us where the water is getting in and we'll send it to local Ottawa waterproofing contractors, who reply by email. We send it out to local contractors for you. Free, no pressure.