Backflow testing runs on a municipal clock, not a provincial one — worth knowing before you assume your building’s rule matches the one down the street.
Short answer
In Toronto, yes: the city’s Water Supply By-law requires every backflow prevention device to be tested “at least once a year”, plus at initial installation and again within 72 hours of any cleaning, repair, replacement or overhaul. Because this sits in a municipal bylaw rather than a provincial regulation, the exact interval and testing regime is set city by city — check your own municipality’s water bylaw rather than assuming Toronto’s applies.
The program is specific about who can sign off on a test: testers must be “plumbers, engineers and fire system sprinkler fitters certified as Cross Connection Control Specialists”, with the criteria for that certification set out in Schedule 6 of the Water Supply By-law. Every device on a property is tested individually — a building with several backflow preventers doesn’t get to test one and extrapolate.
The once-a-year clock isn’t the whole rule. A device also has to be tested the moment it is installed, and again “within 72 hours after a device has been cleaned, repaired, replaced, serviced or overhauled” — which means a maintenance callout can reset the clock on its own, independent of when the annual test is due. Testers must also register with the city’s Backflow Program before conducting any test on a Toronto property; a test performed before that profile exists doesn’t count.
Cross-connection control sits with the municipality that operates the water system, so the frequency, the qualifying certification and the registration requirement are all set at the city level rather than by a single Ontario-wide rule. Treat Toronto’s requirements as an example of the shape a bylaw like this takes, not as the answer for every municipality — confirm the local water bylaw for the property in question, the same discipline that matters for fire alarm testing, where the technical standard is national but the enforcement sits with the province.
This also means the consequence of missing a year isn’t written into a single provincial statute you can look up once. A device that hasn’t been tested on schedule is simply out of compliance with the local bylaw from the day the deadline passes, and because registration with the city’s Backflow Program is a precondition of a valid test, a property that lets its registration lapse can find itself out of compliance even with a technician standing by ready to test.
A 30-minute call is enough to tell you whether your building's cross-connection paperwork is where it needs to be.
