Backwater valve in St. Catharines: the FLAP rules and code.

A backwater valve by itself does not qualify for the St. Catharines Emergency FLAP rebate. The City requires the weeping tiles and any other stormwater connections to be shown disconnected from the sanitary sewer too, before the valve work counts.

Three ways to meet the weeping-tile requirement

A homeowner can demonstrate the weeping-tile and stormwater-connection requirement one of three ways: disconnecting weeping tiles from the sanitary sewer and reconnecting them to a sump pump system (itself an eligible expense); providing documentation that the weeping tiles were previously disconnected; or providing documentation, such as a CCTV or camera inspection, that there are no weeping tiles or stormwater connections tied into the sanitary lateral at all.

The qualifying valve type, and why the exclusions exist

The eligible-works list names the valve type precisely: a mainline backwater valve, normally open design. Two valve types are excluded by name: exterior backwater valves, such as an Adapt-a-valve, and normally closed backwater valves. That is not an arbitrary program choice; it tracks the Ontario Building Code directly. A backwater valve installed in a building drain must be a normally open design conforming to CAN/CSA-B70, CAN/CSA-B181.1, CAN/CSA-B181.2, or CAN/CSA-B182.1, and it may not serve more than one dwelling unit. An exterior device sits outside the building drain rather than in it, and a normally closed design is not the permitted type. Both are excluded because the Code does not permit them in that location, not because the program picked favourites.

New construction, retrofits, and semi-detached homes

For new construction, the Code requires a backwater valve wherever a fixture sits below street level, or, for a home on a public sanitary sewer, below the upstream sanitary manhole cover. In practice, nearly every basement fixture in a sewered St. Catharines neighbourhood, which is why backwater valves have been installed on new construction since 2012. For an existing home, nothing in the Building Code compels a retrofit: the Code governs construction, and the requirement attaches when plumbing work happens under a permit, not to a house standing untouched. That is the real reason a pre-2012 St. Catharines home installs a backwater valve: the rebate is the reason, not the Building Code.

Semi-detached homes have their own rule: each side needs its own backwater valve, not a shared one, because a normally open valve is not permitted to serve more than one dwelling unit.