Backflow Preventer Testing for Commercial Buildings: Annual Requirements in Canada and the US

If you manage a commercial property, sooner or later a letter arrives from the water utility asking for a backflow test report by a certain date. Many property managers inherit this obligation without knowing which devices they have, where they are, or who tested them last. This post explains what backflow prevention is, why the testing is required, and how to keep it from turning into a scramble every year.

What backflow is and why cities care

Normally, water flows from the city main into your building. Backflow is when it flows the other way. It can happen two ways:

• Back-siphonage, when pressure in the city main drops (a main break, firefighting nearby) and water is pulled backward out of the building.
• Back-pressure, when pressure inside the building is higher than in the main, for example from a boiler, a booster pump or a sprinkler system.

If a building has a cross-connection, meaning any point where drinking water could meet something that is not drinking water, backflow can pull contaminants into the public system. Think of boiler chemicals, irrigation water with fertilizer, lab sinks, car wash systems, commercial kitchen equipment, or stagnant water in a fire sprinkler line.

That is why municipalities require backflow prevention devices on many commercial, industrial and institutional connections, and why they require the devices to be tested.

The rules in Canada

In Canada, backflow prevention is driven by the plumbing code and by municipal bylaws. The technical standards are CSA B64.10, which covers selection and installation of backflow preventers, and CSA B64.10.1, which covers their maintenance and field testing.

Each municipality decides how it enforces these. Some examples of how it works in practice:

• Toronto has backflow prevention requirements in its water supply bylaw (Municipal Code Chapter 851). Properties that require a device must have it tested by a qualified tester when installed and then annually, with the results submitted to the city.
• Many Ontario municipalities, including cities in the Waterloo Region such as Cambridge, run similar cross-connection control programs with annual test reporting.
• In British Columbia, municipalities such as Vancouver and others in Metro Vancouver require testing by a certified tester, typically annually, with reports filed with the city.
• In Quebec, requirements come from the provincial plumbing rules and municipal bylaws, and Montreal and other cities have their own programs for commercial and industrial buildings.

The details, including deadlines, submission portals and fees, vary city to city. Your utility's notice is the best guide to what your specific property must do.

The rules in the US

In the US, the Safe Drinking Water Act puts the responsibility for protecting public water on the water system. States and local water utilities then set cross-connection control programs, and the EPA publishes a cross-connection control manual as guidance. Most programs require annual testing of testable backflow assemblies by a certified tester, with reports sent to the water purveyor. Many testers are certified through programs that follow ASSE or ABPA standards, and some states run their own certification.

As in Canada, the exact rules depend on your state and water utility.

Which devices need testing

Not every backflow device is testable. The ones that usually are:

• Reduced pressure principle assemblies (RP or RPZ): used for high-hazard connections such as chemical feed systems, labs, medical facilities and many industrial uses. They have a relief valve that discharges water if the device detects a problem.
• Double check valve assemblies (DCVA): used for lower-hazard connections. Common on fire sprinkler systems without added chemicals.
• Pressure vacuum breakers and spill-resistant vacuum breakers: common on irrigation systems.

A building may have several devices: one at the main service entrance (premise isolation), and others at individual pieces of equipment (point-of-use isolation). Make a list with the location, type, size, make, model and serial number of each. It saves time every year.

How the annual test works

A certified tester connects a differential pressure gauge to the test cocks on the assembly, shuts off the downstream valve, and checks that each check valve holds and that the relief valve (on RP assemblies) opens at the correct pressure. The test takes minutes per device once the tester has access, but water to whatever the device serves is interrupted briefly.

Plan for:

• Access. Devices are often in mechanical rooms, ceiling spaces or below-grade vaults. Make sure the tester can reach them.
• A short shutdown. Coordinate with tenants, kitchens and anything that cannot lose water, such as medical equipment.
• Fire systems. Testing a sprinkler backflow may require notifying the monitoring company and the fire alarm contractor.

When a device fails

Devices fail tests for normal reasons: debris on a check valve seat, worn rubber parts, a relief valve that sticks. Often a rebuild with a repair kit fixes it, and the device is retested and passes the same day or shortly after.

Sometimes replacement is the better choice:

• The device is old and parts are no longer available.
• It keeps failing year after year.
• The hazard has changed (a new tenant with chemical processes) and the existing device type is no longer adequate.
• The installation does not meet current code, for example an RP installed where its relief discharge has nowhere to drain.

Replacing a large device at the service entrance is a real project. It can involve a planned water shutdown for the building, coordination with the utility, a permit in some cities, and drainage for the relief valve. It is much easier to plan this in advance than to do it under a compliance deadline.

Keeping it under control

1. Build a device inventory and keep it with your building records.
2. Book testing on the same month every year, ahead of the city's deadline.
3. Keep every test report and repair invoice.
4. Note any device that has failed twice and plan its replacement.
5. Review the inventory whenever a tenant or a use changes.

Backflow testing and replacement are part of our commercial plumbing work for property managers in cities such as Toronto and Cambridge, and it often goes with other building-level work such as water supply repiping. You can see our service area on the locations page.

Frequently asked questions

How often does a commercial backflow preventer need to be tested?

In most Canadian municipalities and US water utilities, testable backflow assemblies must be tested when installed and then once a year. The test has to be done by a certified tester, and the report is sent to the city or water purveyor. Your utility's notice sets the exact deadline and submission method.

Who is allowed to test a backflow preventer?

Testing must be done by a qualified or certified backflow tester. In the US, many testers are certified through programs that follow ASSE or ABPA standards, and some states run their own certification. In Canada, municipalities require a qualified tester working to CSA B64.10.1.

Does backflow testing shut off the water?

Briefly, yes. The tester closes the downstream valve while checking the assembly, so whatever that device serves loses water for a short time. Coordinate with tenants, kitchens and any equipment that cannot lose supply, and notify the fire monitoring company if a sprinkler backflow is being tested.

What happens if a backflow device fails its test?

Often the device can be rebuilt with a repair kit and retested, sometimes the same day. Replacement makes more sense when parts are no longer available, the device fails year after year, the hazard has changed, or the installation does not meet current code.

Get help with backflow testing or replacement

Send us the property address, what your city's notice says, and anything you know about the devices on site. We will reply with next steps and a written quote. Use the quote form.