Why did my backflow device test fail

Why did my backflow device test fail?

Backflow Device Test

Backflow preventer

Left shows check valve covered in debris, Right is a new check valve.

Backflow preventer parts

Backflow preventer check valve

If you’ve just had your annual backflow device tested but your device failed, you may have a lot of questions as to the reason. These devices are mandatory by law to be tested every year and a passed test needs to be submitted to your municipality in a certain amount of time. Talk about pressure!

A backflow device test fail can feel daunting but to help you understand the reason why these devices fail, here are our findings after years in the business.

Why a backflow device test can fail

Debris – The incoming water from the City can contain microscopic debris from the pipe. If there isn’t a strainer before the device to catch this debris it can settle on the moving parts of the device. This can mean trouble when the parts are then supposed to create a good seal during testing. Debris can sometimes be cleaned off the check valves and the device flushed with clean water before testing to help ensure the device will pass its test. If this is tried and the device still fails, the parts will have to be replaced.

Rusted check valves – Similar to debris, rust from inside the device or piping can cause the mechanical components to seize or stop working correctly. If the device has metal components and fails its test, the parts often have to be replaced. If the components are too sized the whole device would have to be replaced.

Stuck relief valve – In the case of a Reduced Pressure device, the relief valve can often seize in the open or closed position. This is not ideal as it is only supposed to open once the device is engaged and then close again. If it gets stuck in the open position it is impossible to test correctly. If malfunctioning, it would require the replacement of just the relief valve.

Old/corroded device – If the device is over 25 years old or in a very badly corroded state and also fails its annual test, it should be replaced. The mechanical parts are probably compromised and a new device should be installed.

Extreme heat – Unless your device is rated for high heat any hot/warm water will degrade the mechanical components inside. A premise protection device is always on the incoming cold water so heat is never an issue for this device. However, some companies are mandated to install zone isolation devices on hot lines and that is when a special device that can handle high temperatures is used.

High use devices – If your device is in a production facility that uses water 24/7, the constant flow of water can degrade the seals faster in the check valves. These components can be switched but it will require water shut down.

Defective shut off valve – In order for the test to be performed shut off valve 2, in-front of the device, needs to completely close. If this valve does not close or seal properly the test cannot be performed.

What to do after the backflow test fails

Based on the reason for the backflow device test fail you can more than likely get replacement parts. With supply shortages, getting parts is now harder than ever. If the device is very old or no longer being made, parts could be even harder to get or non-existent. In cases where parts are hard to get or very long lead time, we can replace the whole device. Replacement is sometimes the quickest solution but often requires a building permit.

If your backflow device test failed and are looking to get it repaired or replaced, call the trusted plumbers at Trouble Shooters. We are an approved contractor for the testing, installation, and maintenance of commercial backflow preventers in the Province of Ontario.

If you have more questions on how these devices work, visit our Backflow Preventer page to learn more.

Contact Trouble Shooters for professional plumbing service in Toronto and Scarborough