Backflow prevention testing

Inside every backflow assembly, spring-loaded checks hold building water on its own side so it can never siphon into the municipal main. It only works if its check valves seal, which is why the device has to be tested.

Cause found and explained before any work starts

On the van: Calibrated differential pressure test kit, repair kits, seat tools, valve keys

Finished with: All checks and relief valve meet required pressure differentials

Booked by phone anywhere in North York

What a backflow device does

Keeps water from boilers, sprinklers, irrigation, process equipment or chemical feeds out of the drinking supply.
Sits after the water meter, usually where the main enters the building.
Common types: reduced pressure zone (RP) assemblies and double check valve assemblies.
Smaller devices protect single pieces of equipment like a boiler fill or soda machine.

Plumber's tip: The City of Toronto has required a wide range of ICI and multi-residential sites to install premise isolation devices and test them on a schedule, with results submitted to the City. Requirements change; confirm the current rules and deadlines with the City before booking.

Signs your device needs attention

A test notice or reminder from the City.
Water discharging from the relief valve on an RP assembly.
Pressure drops on the building side after the device.
A device that has never been tested since it was installed.
New equipment added that creates a cross-connection.

How the test runs

We agree a time with you, since water to the building is briefly interrupted.
The device is identified by make, model, size and serial number.
Hoses from our calibrated differential gauge go onto the device's test ports.
We read the drop across check one, check two and the relief opening point, and compare each to its minimum.
Shut-offs are restored slowly and the building side is checked for pressure.
Results are recorded and the report is prepared for submission.

When a device fails

Grit lodged under a seat is the usual culprit, and a cleaning frequently brings the device back to a pass.
Worn rubber parts are replaced with the manufacturer's repair kit.
A damaged body or an obsolete model may need replacing; that can need a permit.
The device is re-tested after any repair before it goes back in service.

Properties that usually need this

Restaurants and food plazas.
Medical and dental clinics.
Condo and rental buildings with boilers or fire lines.
Light industrial units along the Highway 401 and Dufferin corridors.

Job at a glance

What we bring and how we check it
Category	Commercial
Tools	Calibrated differential pressure test kit, repair kits, seat tools, valve keys
Final test	All checks and relief valve meet required pressure differentials

Tell-tale signs

City test notice received
RP relief valve dumping water
Device never tested since installation

Steps on the job

Record make, model, size and serial
Hook a calibrated gauge to each test port
Test each check and the relief valve
Restore flow slowly and prepare the report

Your questions on this one

How long does a backflow test take?

For one assembly, plan on roughly an hour or less, longer when there are several or one fails and needs repair.

Will the water be shut off?

Briefly. The test needs the device isolated, so we schedule it when a short interruption does the least harm.