waterdamagequotesThe device · and the nine programmes that fund it
Backwater valves: what they cost, who pays part of it, and which type you are allowed to install
A backwater valve is the lowest-priced device on this site that can stop the most expensive kind of water. It is also the one that is sold under the largest number of names, installed in two places that are not interchangeable, subsidised by nine Ontario programmes with nine different rules, and capable of flooding your basement by working exactly as designed.
This page puts what governments publish about the device in one place: what it is, which type you are allowed to install, what the only published installed prices in Ontario are, who pays part of the bill, and the maintenance intervals five different public bodies recommend — which do not agree.
The short version
- Canada’s federal guidance describes two types of valve. Toronto permits one of them and prohibits the other in writing.
- Under the Ontario Building Code, as the Region of Peel states it, one valve serves one dwelling unit — a basement apartment needs its own.
- The only published installed prices in Ontario are Hamilton’s five pre-qualified contractors: $1,292 to $1,562 plus HST for an assessment and a mainline backwater valve, across five pre-qualified contractors.
- Nine Ontario programmes pay part of it, from $1,200 in Niagara Falls to $2,500 in Ottawa, and two of them will not pay at all if the work has already started.
Five names, one device
Half the confusion in this category is vocabulary. The phone call, the quote, the permit and the by-law each use a different word for the same object, and two of those words describe genuinely different devices.
| What you would say | What the quote, permit or by-law calls it | What it changes |
|---|---|---|
| Backwater valve | Mainline backwater valve | The one on the pipe leaving the house. This is the device every subsidy is about. |
| Sewer backflow valve | Backwater valve | Same thing. The federal guidance gives both names in its first sentence. |
| The flap | The gate | Ottawa describes it as open and parallel with the lateral in normal use, perpendicular when it closes. |
| A valve on the sewer pipe | Sanitary lateral valve | Protects against sewage backing up. This is what Peel’s rebate is for. |
| A valve on the sewer pipe | Storm lateral valve | A different pipe. Mississauga and Ottawa fund this one; it protects against storm water backing up the line your weeping tile drains into. |
| Normally open valve | Fullport valve | The type Toronto permits. It sits open and closes on backflow. |
| Normally closed valve | — | Prohibited in a Toronto building drain or building sewer. Worth checking before you buy one. |
| The cap on top | Cleanout cap / access cover | The federal page says valves can fail if it is not secure. It is also how you clean the valve. |
| A second valve | A valve per dwelling unit | A basement apartment requires its own, because of the Building Code rule Peel publishes. |
| An alarm | Valve alarm | Tells you the valve has closed, which is the moment you must stop using water. |
| “The Hamilton one” | Adapt-a-valve | A variant Hamilton prices separately from a mainline valve, at a different figure, across the same five firms. |
| Permit | Standalone plumbing or drain permit | Required in Toronto, Ottawa and Peel. Missing it is the most common way a subsidy application fails. |
What the gate actually does
Government of Canada, Get Prepared — Backwater valves · 2026
The federal page adds that the one-way valve “allows wastewater to flow out of your home, and securely closes when backups or backflow is detected”, and that they are also called sewer backflow valves. Page last modified March 23, 2026.
The mechanism is worth understanding because it explains both why the device works and how it can turn on you. The City of Ottawa describes it in the plainest language any public body uses:
City of Ottawa, Residential Protective Plumbing frequently asked questions (PDF) · 2025
The City continues: when sewer surcharging occurs, wastewater or stormwater entering the lateral “causes the gate to close or become perpendicular with the lateral”, preventing it entering the home. Ottawa also states that a backwater valve is installed on a sanitary or storm sewer lateral — which is why two cities here fund two different valves.
So the valve is not a pump, a filter or a one-time installation you can forget. It is a hinged plate that spends its whole life open, in a pipe that carries everything your household sends down a drain, and it has to move freely on the one day a decade when it matters.
Sanitary or storm: two pipes, two valves
Ottawa’s own wording is that a valve is installed on a sanitary or storm sewer lateral, and that distinction is not academic. In Mississauga the weeping tile around your foundation drains to the City’s storm sewer, so the City’s rebate option puts a valve on the stormwater lateral. In Peel Region — the same address, a different government — the rebate is for a valve on the sanitary lateral. A Mississauga homeowner sits inside both programmes at once, on two different pipes.
City of Mississauga, Basement Flooding Prevention Rebate · 2026
Mississauga's weeping tiles drain to the storm sewer, which is why its Option 2 puts a backwater valve on the stormwater lateral. London's and Niagara Falls' problem is the opposite connection — weeping tiles into the sanitary sewer. The device you need depends on which pipe your foundation drains into, and that is a municipal fact, not a national one.
Normally open, normally closed, and the one Toronto prohibits
Government of Canada, Get Prepared — Backwater valves · 2026
The federal description of a normally open valve. A normally closed one, the same page says, opens “only in one direction when wastewater is discharged”. Which of the two you are allowed to install is a municipal question, and Toronto answers it in writing.
Federal guidance describes both types without ranking them. Toronto’s building permit guide is not so neutral:
City of Toronto, Building permit application guide — Backwater valve · 2026
The same guide states that a valve “designed to be installed in a normally closed position is prohibited from being installed in a building drain or building sewer”. So the federal page describes two types and Toronto permits one of them. Page last modified July 14, 2026.
This is the single most checkable thing on this page. If a quote names a valve type, that name can be read against the City’s own permit guide before anybody digs up a floor. If the quote does not name a type, that is the question to ask.
One dwelling unit, one valve
Region of Peel, Sanitary backwater valve rebate · 2026
The Region adds: “A basement apartment will require its own valve.” This is the single most consequential sentence on this page for anyone with a second unit, and it is the reason a quote for one valve sometimes comes back as a quote for two.
Anyone with a basement apartment, an in-law suite or a second registered unit should read that sentence twice. It is why a quote for a duplex comes back at roughly double, and why a single valve on a two-unit house may not pass the inspection that releases a rebate.
Where it has been mandatory, and for how long
City of Ottawa, Residential Protective Plumbing frequently asked questions (PDF) · 2026
Which is a fast way to know whether you are likely to have one: if the house is older than that and nobody retrofitted it, you almost certainly do not.
That is a fast way to work out whether you are likely to have one at all. In Ottawa, a house built before 2004 with no retrofit almost certainly does not. The Government of Canada is blunt about who should do the retrofit:
Government of Canada, Get Prepared — Backwater valves · 2026
The same page tells you to check with your local government about regulations such as permits or inspections required before installation — which is the step that disqualifies people from municipal rebates more often than any other.
What it costs, from the only cities that publish it
Every other page answering this question gives you a national average. There is no such measurement, and this site does not manufacture one — the reasoning is on the cost page and in the methodology. What exists instead is one municipality that negotiated fees with named contractors and published them.
| Contractor | Mainline backwater valve | Adapt-a-valve |
|---|---|---|
| Stokoe Plumbing Inc. | $1,292 + HST | $1,292 + HST |
| Hamilton Sewer & Water Services Inc. | $1,444 + HST | $1,444 + HST |
| Orella Group Inc. | $1,523 + HST | $1,955 + HST |
| Rooter Guys Inc. | $1,554 + HST | $1,554 + HST |
| The Plugged Piper Drain Service Inc. | $1,562 + HST | $2,505 + HST |
City of Hamilton, Protective Plumbing Program, pre-qualified contractor fee table · 2026
The adapt-a-valve variant runs from $1,292 to $2,505 plus HST across the same five firms. The building permit is $291 and downspout disconnection is $75 plus HST per downspout. Five firms is a small sample and it is one city, and this site says so rather than calling it a national average.
Five firms, one city, one device, published by the city that negotiated the prices. That is a real sample of something, and it is a small one — which is why it is presented as five Hamilton quotes rather than as what a valve costs in Canada.
The permit is not the same fee twice
| City | Published figure | What the figure is |
|---|---|---|
| Hamilton | $291 | The building permit fee for a backwater valve installation, published beside the contractor fee table. |
| Toronto | $38.67 each | A per-item plumbing fee line inside a standalone drain permit application, not the whole cost of permitting the job. |
| Ottawa | Fully rebated | The City refunds the permit fee on submission of the permit and the inspection report. |
City of Toronto, Building permit application guide — Backwater valve · 2026
The City's plumbing fee line for “Backwater Valves, Manholes, Catchbasins, Interceptors and Sumps Complete with Pumps”. It is a per-item fee inside a standalone drain permit application, not the whole cost of permitting the job — compare Hamilton, which publishes a $291 building permit fee for the same device.
A company’s own price list, named
One Toronto waterproofing company publishes a price list that includes backwater valve installation at $1,600 – $3,700. It is reproduced here the way this site reproduces every commercial figure: attributed to the firm that published it, never averaged with anything else.
Aquatech Waterproofing, published price list · 2026
One Toronto company's published range for a backwater valve installation. Hamilton publishes $1,292 to $1,562 plus HST across five pre-qualified contractors for an assessment and a mainline valve. Two cities, two scopes, two sources — and a spread wide enough that a single national “average” would be meaningless.
Set the two sources side by side and the useful conclusion is not a number. It is that the same three words on a quote can describe an assessment and a mainline valve in a pre-qualified programme, or a job on a finished basement with a different scope entirely. Ask what the price includes before comparing it to anything.
Nine programmes that pay part of it
Nine Ontario municipal or regional programmes on this site put money towards a backwater valve. They disagree about the amount, the share, the pipe and the order of operations.
| Programme | Maximum for the valve | Share of the invoice | Order |
|---|---|---|---|
| Toronto | $1,600 per device, maximum two devices | up to 80 per cent of the invoiced cost | Apply within two years after installation |
| Mississauga | $1,500 (storm lateral) | Not published | Apply after the work |
| Region of Peel | $1,500 (sanitary lateral) | 60% of the invoiced amount | Permit first, then install, then inspection, then apply |
| Ottawa | $2,500 (exterior storm valve) | Not published; the lesser of the maximum or the cost | Permit required |
| Hamilton | Within the $2,000 grant, or $500 with your own contractor | Not published | Contractor from the City list for the full grant |
| London | $1,800 | 90% of total cost | Do not start construction first |
| Windsor | $1,450 | Not published | Apply and be approved before any work |
| Niagara Falls | $1,200 including taxes | 100% of eligible costs | One rebate per property |
| St. Catharines | Within one $5,000 pot for all devices (normally open valves only) | 90% of eligible costs | Apply before any work |
City of Niagara Falls, Weeping Tile Removal Assistance Program · 2026
Item 2 — backwater valve installation. It is the lowest published valve maximum of the nine Ontario programmes on this site (Edmonton's, in Alberta, is $800) and the only one that states it is paid at 100 per cent of eligible cost including taxes.
The spread between the largest and smallest published valve maximum here is roughly a factor of two, and the share matters as much as the maximum: a programme that pays a smaller share of a larger cap can return less money than one that pays all of a smaller cap. The provincial hub lays the six main programmes out side by side.
The order of operations that voids the cheque
City of Windsor, Basement Flooding Protection Subsidy Program · 2026
The City adds that any work performed by the homeowner, or completed prior to approval, will not be eligible for a subsidy. Read against Toronto, where you apply within two years after installation, these are opposite instructions for the same device.
Two of these programmes will not pay for work that is already under way, and one of them will not pay for work you did yourself. Toronto, at the other end, accepts applications up to two years after installation. Same province, same device, opposite instructions — so the order is a thing to check against your own city’s page before the plumber books a date.
Region of Peel, Sanitary backwater valve rebate · 2026
The Region's own step order: permit first, then install, then inspection, then the rebate application — which is submitted only after the valve has passed inspection.
Five publishers, five maintenance intervals
A backwater valve is a moving part in a sewer. Every public body that publishes guidance on it publishes a maintenance interval, and they are not the same interval — which is itself worth knowing, because a contractor quoting you an annual service contract is quoting one of these and not another.
| Who publishes it | Interval | What the task is |
|---|---|---|
| Government of Canada | at least once a year in the spring | Inspection and maintenance by a plumber, depending on the type of valve. |
| Government of Canada | At least twice a year | Cleaning, to remove dirt and grease buildup. |
| City of Toronto | Annual cleaning | Via the clean-out ports, plus inspection to the manufacturer’s directions. |
| City of Ottawa | maintained periodically or before a forecasted heavy rainfall | Free of debris, functioning properly, caps and covers firmly secured. |
| Region of Peel | At least once a year, or before a forecasted heavy rainfall | Inspect and clean. |
| EPCOR (Edmonton) | Spring and fall | Check and clean the sanitary backwater valve, and check the O-ring. |
| IBC and ICLR | At least once a year | Maintenance, alongside a recommended installation grade of at least 2%. |
Government of Canada, Get Prepared — Backwater valves · 2026
The cleaning steps end with a warning that is easy to miss: “Tightly secure the cap. Backwater valves can fail if the cleanout cap is not secure.”
The two failure modes the utilities describe are mechanical and dull, which is what makes them believable:
EPCOR Edmonton, Backwater valve · 2026
EPCOR's other check is the one no municipal page in Ontario mentions: “Check the O-ring on the backwater valve. If it's cracked or damaged, replace it.” Its seasonal maintenance guidance puts the valve check in both the spring and the fall list. EPCOR is the water utility for Edmonton and is cited here for the maintenance detail, not for an Ontario rule.
Published July 17, 2025. The grade is the detail worth carrying into a quote: a valve installed flat is a valve that collects what it is supposed to pass.
The grade is the one to carry into a quote. A valve installed flat collects what it is supposed to pass, and the homeowner finds out during the storm.
The self-flood: when the valve working is the problem
City of Toronto, Basement Flooding Protection Subsidy Program · 2026
The failure mode nobody warns you about when they sell you the valve: the device works, and then the household floods itself from the inside. It is why the alarm is worth more than it costs.
This is the part that gets left out of the sales conversation. While the valve is closed against the sewer, your own household water has nowhere to go either. Ottawa puts it as: do not shower, flush toilets or wash clothing until the system has returned to routine functioning. EPCOR and Peel say the same thing in their own words.
Government of Canada, Get Prepared — Backwater valves · 2026
The federal page's reason for wanting one: it “will help you avoid causing a ‘self-flood’ by using excess water when the valve is closed”. Toronto, Ottawa, Peel and EPCOR all publish the same instruction in different words — when the valve is shut, stop using water.
Which is the argument for the alarm. The valve closes silently, underground, usually during a storm, usually at night. Without a signal, the first indication that it has done its job can be the washing machine draining into the floor drain it is no longer able to reach.
City of Toronto, Basement Flooding Protection Subsidy Program · 2026
Toronto's subsidy conditions also say not to enclose or cover the valve before the inspection is complete — a finished basement built over an unlocated valve is a common and expensive way to lose access to it.
What it does for your insurance, and what it does not
Insurance Bureau of Canada, Water Damage and Flood Protection · 2026
IBC's list of what a homeowner can do, and it defers to the municipality rather than setting its own rule. The same page says “some insurers may also provide incentives for installing backwater valves and/or sump pumps” — may, some, incentives. It is not a discount you can assume, and this site does not tell you which insurers do it, because IBC does not say.
Read that carefully, because the version you will hear is stronger than the version the industry association actually publishes. IBC says some insurers may provide incentives. It does not say a valve earns a discount, it does not name a figure, and it does not name a company — so neither does this site.
Insurance Bureau of Canada, Water Damage and Flood Protection · 2026
IBC's wording is unambiguous: “Damage caused by the backing up of sewers and drains is typically not covered by a standard policy.” It adds that “optional sewer backup is offered by most insurers” — so the cover exists, it is just not switched on by default.
The more important point is the one that survives whatever your insurer does: the valve and the endorsement protect against the same event from opposite ends. A valve tries to keep the sewage out of the house. The sewer backup endorsement is what pays when it gets in anyway. Neither substitutes for the other, and a standard Canadian policy includes neither.
Government of Canada, Get Prepared — Backwater valves · 2026
The federal page's figure for the average cost to repair a flooded basement, which it says could also impact your insurance premium. It is the only average repair figure on this site with a government source, and it is a national average rather than a quote for your basement.
Why this site has nothing to gain from your answer. We are paid a fixed amount for each enquiry, agreed before it is sent. It does not move with the size of the job, with whether you book anything, or with which company you pick. So there is no version of this page where steering you is worth anything to us — which is also why you will not find a company named, rated or recommended anywhere on this site.
Questions people actually ask
How much does a backwater valve cost in Ontario?
The only published installed prices are Hamilton's. The City lists five pre-qualified contractors at $1,292 to $1,562 plus HST for an assessment and a mainline valve, and a separate $291 building permit fee. A Toronto waterproofing company publishes $1,600 to $3,700 for an installation on its own price list. Those are two cities and two scopes, not a national average, and this site does not publish one.
Which type of backwater valve am I allowed to install?
In Toronto, a fullport normally open valve conforming to the appropriate CSA standard may be installed in a building drain serving one occupancy, and a valve designed to be installed in a normally closed position is prohibited in a building drain or building sewer. Federal guidance describes both types; the permitted type is a municipal question.
Do I need a permit for a backwater valve?
Toronto requires a building permit as a condition of its subsidy, Ottawa requires one for any protective plumbing device and refunds the fee, and the Region of Peel tells you to apply for a permit from your local municipality before installing. Federal guidance simply says to check with your local government about permits or inspections required before installation.
Does a basement apartment need its own valve?
The Region of Peel states that under the Ontario Building Code a backwater valve can only be installed on the sanitary pipe that serves one dwelling unit, and that a basement apartment will require its own valve.
How often does a backwater valve need maintenance?
It depends whose guidance you follow. The Government of Canada recommends a plumber inspect it at least once a year in the spring and that it be cleaned at least twice a year. Toronto publishes annual cleaning via the clean-out ports, Peel at least once a year or before forecasted heavy rainfall, Ottawa periodically or before heavy rainfall, and EPCOR in both spring and fall.
Will a backwater valve lower my insurance premium?
The Insurance Bureau of Canada says some insurers may provide incentives for installing backwater valves and sump pumps. That is the whole of what the industry association publishes: may, some, incentives. Sewer backup coverage itself is not part of a standard policy and has to be bought as an endorsement.
Can I use the sink while the valve is closed?
No. Toronto's guidance is that when the valve is closed you should not use any plumbing fixtures, because water will not drain and will back up into your home. Ottawa says not to shower, flush toilets or wash clothing until the system has returned to routine functioning. An alarm is what tells you the valve has closed.
Where to read next
- Weeping tile: the other half of the same system
- Sump pump cost and the rebates for it
- Every Ontario programme, side by side
- The endorsement that pays when the valve does not
- What a sewer backup actually does to a house
- Hamilton: the city that publishes its prices
- Hamilton backwater valves: the whole-job totals
Sources cited on this page
- Government of Canada, Get Prepared — Backwater valves
- City of Toronto, Building permit application guide — Backwater valve
- City of Toronto, Basement Flooding Protection Subsidy Program
- City of Ottawa, Residential Protective Plumbing frequently asked questions (PDF)
- City of Ottawa, Residential Protective Plumbing Program
- Region of Peel, Sanitary backwater valve rebate
- City of Hamilton, Protective Plumbing Program, pre-qualified contractor fee table
- City of Hamilton, Protective Plumbing Program
- City of London, Basement Flooding Grant Program
- City of Windsor, Basement Flooding Protection Subsidy Program
- City of Niagara Falls, Weeping Tile Removal Assistance Program
- City of Mississauga, Basement Flooding Prevention Rebate
- EPCOR Edmonton, Backwater valve
- Insurance Bureau of Canada, Water Damage and Flood Protection
- Insurance Bureau of Canada and Institute for Catastrophic Loss Reduction, Good, Better, Best Basement Flood Protection
- Aquatech Waterproofing, published price list
Every figure above was read from the source it is attributed to on September 20, 2026. How we check this.
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