Backwater valve in Toronto: the permit, the fee and the paperwork.

Toronto's subsidy pays up to $1,600 toward a backwater valve, but the City expects the job done in a set order: a building permit first, an inspection before the valve is covered, then an application with the right invoice. Here is that order, with the permit fee Toronto Building charges in 2026.

The order the City expects

• Before work starts, check that the contractor and any sub-contractors hold a valid City of Toronto business licence, with the Business Licence Lookup tool or by calling 416-392-6700.
• Get a building permit to install the backwater valve.
• Request an inspection once the valve is in. Do not enclose or cover it before the inspection is complete.
• At the inspection, or whenever the City asks, the owner consents to City access to the valve and to photographs, video and digital images of it.
• Apply online within two years of the installation, with the original electronic invoice from each licensed contractor.

What the permit costs in 2026

Toronto Building's 2026 fee schedule lists backwater valves under Other Plumbing Work at $38.67 each. The same schedule sets a minimum fee of $214.79 for all work. One or two valves at the per-valve rate come to less than that, so a permit for the valves alone is charged the minimum.

Starting before the permit is issued costs more. The schedule adds a charge for construction without a permit of 50% of the permit fee or $214.79, whichever is greater.

The subsidy page lists labour, materials and taxes as eligible costs for a backwater valve. It does not say whether the permit fee counts, so ask the program before you count on it. Its contact is BasementFlooding@toronto.ca or 416-338-7668.

A second valve, and the older cap

For work completed on or after November 12, 2025, the subsidy covers up to 80 per cent of the invoiced cost, to a maximum of $1,600 per device, for up to two backwater valves, alarms included. The City's April 28, 2026 announcement said the second valve is for homes with multiple sewer connections. Work completed before November 12, 2025 falls under the old maximum of $1,250 for one device, and has a one-year filing window instead of two.

The invoice has to show the licensed contractor's name and address, the property address, the date the work was completed, an itemized cost for each device, and the total paid, clearly marked as paid in full. The City says a subsidy can take up to 10 weeks to arrive.

The valve the Code allows

Ontario's Building Code, Article 7.4.6.4, allows a backwater valve in a building drain only if it is a normally open design that meets one of the listed CSA standards, and it may not serve more than one dwelling unit. In new construction it is required wherever a fixture sits below street level or, on a public sanitary sewer, below the upstream sanitary manhole cover. The July 2026 code amendments page explains which version of the Code is in force.

A backwater valve is not a backflow preventer

The names sound alike, but the two devices protect different things. A backwater valve closes the sewer line during heavy rain so water cannot come back up into the house. A backflow prevention device, as Toronto's water supply by-law defines it, stops water from flowing back into the City's waterworks and is tested under the CSA B64 standards.

The 2026 permit fee schedule prices them separately: $38.67 for a backwater valve, and $92.79 for a backflow prevention device that requires testing. The basement flooding subsidy is for the backwater valve.

Living with the valve

When the valve closes during a storm, nothing in the house drains. Do not use the toilets, sinks, dishwasher or washing machine until it reopens, or the water backs up inside. An alarm tells you when it has closed.

The City recommends cleaning the valve once a year through its clean-out ports, and inspecting it as the manufacturer directs. If the house has weeping tiles, they should connect downstream of the valve. A sewage ejector pump is another option, but the subsidy does not cover one. The sump pump caps and the rest of the program are on the Toronto rule card.