A backwater valve installed in a Toronto house costs about $3,800 on average, according to a 2025 City of Toronto staff report, and the City’s Basement Flooding Protection Subsidy Program now pays 80% of the invoice up to $1,600 per valve. That brings a typical job down to roughly $2,200 out of pocket. The install itself is often done in a day or two, but you need a City drain permit and an inspection before the floor is closed up, and the contractor must hold the right City business licence or the subsidy is denied.
Since May 1, 2026, the program covers more than it used to: up to $6,650 per property across a backwater valve, a sump pump, a battery backup, a plumbing assessment and foundation drain capping. Here’s what each piece does, what it costs, and how to make sure you actually get the money back.
What a backwater valve does, and why Toronto homes need one
A backwater valve sits in the main drain line under your basement floor. Normally it stays open and lets wastewater flow out to the City sewer. When a heavy storm overloads the sewer and water tries to flow back up the pipe, a flap closes and stops it from coming out of your floor drain, toilet or shower.
That matters in Toronto because big summer storms are getting harder to ignore. The City’s own report notes that storms in July and August 2024 flooded more than a thousand properties, which is what pushed Council to expand the subsidy. Fewer than one in six eligible owners has used the program since it started in 2007, according to the City.
One rule people don’t know about: the City’s permit guide says only a fullport, normally open valve that meets the CSA standard can go in a house drain. Normally closed valves are prohibited in a building drain or sewer. If someone quotes you a cheaper valve, ask which type it is.
What changed in Toronto’s flooding subsidy in 2026
On April 28, 2026, the City announced it would almost double the subsidy, effective May 1. The maximum per property went from $3,400 to $6,650. The new amounts apply to work completed on or after November 12, 2025, so if you had a valve put in last winter, you may still qualify at the higher rate.
The main changes:
- Backwater valve: up to $1,600 per valve (was $1,250), and homes with more than one sewer connection can now claim a second valve.
- Sump pump: up to $2,250 (was $1,750), plus up to $300 more for a battery backup.
- New home plumbing assessment subsidy: up to $500, one time.
- Foundation drain severance and capping: still up to $400.
- You now have two years after the work is done to apply, instead of one.
Every item is paid at 80% of the invoiced cost, up to its cap. So on a cheaper job you get 80% back, and on a bigger job you hit the cap and pay the difference.
What backwater valve installation costs in Toronto
The best local number we’ve found comes from the City itself. Its October 2025 staff report puts the average market cost of a backwater valve installation at about $3,800. For sump pumps, the City doesn’t publish a figure, so we’ve used the HomeStars sump pump cost guide, which gives Canada-wide numbers rather than Toronto-specific ones.
| Work | Typical cost | City subsidy (work done on or after Nov 12, 2025) | Source |
|---|---|---|---|
| Backwater valve, installed | About $3,800 on average | 80% up to $1,600 per valve, up to two valves | City of Toronto staff report, 2025 |
| Sump pump, installed | About $1,200 on average; $2,500 to $5,500 for complex installs | 80% up to $2,250, one pump | HomeStars cost guide (Canada) |
| Sump pump battery backup | $200 to $600 as an add-on | Up to $300 extra | HomeStars cost guide (Canada) |
| Home plumbing assessment | No published range | 80% up to $500, one time | City subsidy program page |
| Foundation drain severance and capping | No published range | 80% up to $400 | City subsidy program page |
| City drain permit, backwater valve | $38.67 per valve listed; the $214.79 minimum permit fee may apply | Not covered | City building permit fees, 2026 |
A quick example using the City’s average: 80% of $3,800 is $3,040, but the cap is $1,600, so you’d pay about $2,200 for the valve. A $2,500 sump pump job would get $2,000 back, because 80% of it is still under the $2,250 cap.
What pushes the price up or down:
- Floor finish: cutting through bare concrete is cheaper than lifting and replacing tile, a finished floor or a built-in wall.
- Drain depth and location: a deep or hard-to-reach main drain means more digging and more concrete work.
- Pipe condition: old clay or cast-iron pipe found during the dig may need repair before the valve goes in.
- Sump pit: a new pit and discharge line cost more than replacing a pump in an existing pit.
- Bundling: doing the valve, sump pump and drain capping in one visit saves on mobilization and concrete patching.
If you’re planning a basement renovation, put the valve in first. It’s far cheaper to cut the slab before the new floor and walls go down than to open up a finished room later.
Do you need a permit for a backwater valve in Toronto?
Yes. The City’s permit guide lists backwater valves as work that needs a permit, and the subsidy page says you must get a building permit and request an inspection after installation. Don’t cover or enclose the valve before the inspector has seen it. For a house with one or two units, it’s a stand-alone drain permit, no plans are needed, and the City’s backwater valve permit guide lists a 2026 fee of $38.67 per valve. The City’s general minimum permit fee is $214.79, so confirm the total when you apply.
Installing a sump pump is listed by the City as work that does not need a building permit. You still need photos of the pump and its outside discharge pipe for your subsidy application, so take them before anything gets covered.
Who is allowed to do the work?
This is where people lose their subsidy. The contractor and every sub-trade must hold a valid City of Toronto business licence on the day the work is done, and the licence type matters:
- Plumbing (T94), Plumbing and Heating (T92) and Drain (T87) contractors can do all of the eligible work, including backwater valves.
- Building Renovator (T85) contractors can only do the sump pump and the foundation drain severance and capping.
The City suggests checking the licence on its Business Licence Lookup or by calling 416-392-6700 before work starts, and getting at least two quotes. Ask every contractor which licence they hold and who will physically install the valve. If you hire a general contractor, make sure the sub-trade doing the drain work is on the invoice.
How to apply for the subsidy, step by step
- Check you qualify: you must be the registered owner of a single-family home, duplex, triplex or fourplex in Toronto, with no unpaid City taxes or debts.
- Disconnect your downspouts from the sewer, or have a City exemption. It’s an eligibility condition, and front-yard paved areas must also meet the Zoning By-law.
- Optional but useful: book a home plumbing assessment. A plumber fills out the City form, and you can claim up to $500.
- Have the work done by contractors with the right licence, with a permit and inspection for any backwater valve.
- Get an original electronic invoice marked “paid in full”, with the contractor’s name and address, your property address, the completion date and an itemized cost for each device. A sump pump and its battery backup must be itemized separately.
- Apply online within two years of the work, attach the invoices, and allow up to 10 weeks for the City to review it.
Funding is first-come, first-served and depends on Council approving it each year, so applying doesn’t guarantee a payment. Don’t wait two years just because you can.
Is a backwater valve enough on its own?
Not always. A backwater valve only stops sewer water coming back in through the drains. It does nothing about groundwater pushing through cracked foundation walls or water pooling against the house. For that you’re looking at grading, downspouts, foundation repair or proper waterproofing.
If your basement leaks at the walls or floor joint, read up on our basement waterproofing service as well. And if you’re turning the basement into a rental, a valve is cheap insurance for a legal basement apartment, where a flood means an empty unit and a tenant to rehouse. If you’re also planning basement underpinning, the drain work can be planned into the same dig.
Frequently asked questions
How much does backwater valve installation cost in Toronto?
The City of Toronto’s 2025 staff report puts the average installed cost at about $3,800. The City’s subsidy pays 80% of the invoice up to $1,600 per valve, so a typical job ends up around $2,200 out of pocket. HST is extra and every house is quoted after a site visit.
How much will Toronto pay toward basement flooding protection?
Up to $6,650 per property for work completed on or after November 12, 2025. That covers up to two backwater valves at $1,600 each, a sump pump at $2,250, a battery backup at $300, a plumbing assessment at $500 and foundation drain capping at $400, each at 80% of the invoice.
Do I need a permit to install a backwater valve in Toronto?
Yes. A backwater valve needs a stand-alone drain permit, listed at $38.67 per valve in 2026, and an inspection before it is covered. A sump pump installation on its own does not need a building permit, according to the City.
Can any contractor install my backwater valve and still get the subsidy?
No. For a backwater valve, the installer must hold a valid City of Toronto Plumbing, Plumbing and Heating, or Drain business licence on the day of the work. Building Renovator licence holders can only do the sump pump and foundation drain capping.
How long do I have to apply for the subsidy?
For work completed on or after November 12, 2025, you have two years from installation. For older work, the limit is one year. The City says review can take up to 10 weeks.
Want a straight answer on flood protection for your basement?
We’ll look at your basement, your drains and your plans for the space, and tell you what makes sense before you finish anything. We carry $2 million in liability insurance, back our work with a 5-year workmanship warranty, and have more than 15 years of experience in the GTA. Request a free estimate or call us at 647-642-4664.
