Backflow preventer testing and installation
Backflow devices keep water inside a building, sprinkler system or process line from siphoning back into the town mains. It has to be the right type, installed correctly and tested.
- Testable assemblies checked using a calibrated gauge kit
- Failed devices rebuilt or replaced
- New installs sized for the hazard and pipe size
- Test results recorded for Regional filing where required
- Licensed plumbing trade
- Camera before digging
- Written job notes
- Phone-only booking
Where backflow devices are found
- Water service entries to commercial, industrial and institutional buildings
- Lawn irrigation systems connected to the domestic water line
- Restaurant equipment such as carbonators, coffee machines and dish machines
- Fill lines feeding boilers and hydronic heating loops
- Farm and greenhouse lines with chemical injectors north of Brooklin
What happens during a test
- Confirm the device type, size and serial number match the records
- Close the downstream shut-off and connect the test kit to the test cocks
- Read both check valves and the relief valve against that model's pass numbers
- Rebuild or replace parts if the device fails, then retest
- Record the results and reopen the water supply
Why devices fail
Check valves hold back pressure with springs and rubber seats. Over time debris lodges in the seat, rubber hardens and springs weaken. Freezing can crack the body of a device installed outdoors or in an unheated room. A device that fails its test is not protecting the supply until it is repaired.
- Debris on check valve seats after water main work
- Hardened or torn rubber parts
- Frost damage on outdoor and unheated installations
- Relief valve discharging constantly
Regional requirements
Under its water by-law, Durham Region has run a cross-connection program, which has required many non-residential properties to install and test devices and submit results. Ask the Region what applies to your site today, because program details get revised.
Common questions
How often must a backflow device be tested?
Regional programs have commonly required testing at installation and then yearly. Verify your own testing interval with the Region.
Does a house need a backflow preventer?
Most houses rely on simpler protection, but irrigation systems and some equipment need their own device.