How to Test a Backflow Preventer

The only thing standing between your clean drinking water and pollutants or chemicals in Calgary is a simple yet ingenious piece of piping equipment called a backflow preventer.


A typical backflow preventer is made of test cocks and shut-off valves that only allow water to flow in one direction. Its purpose is to control cross-connections and prevent a backflow of contaminants into potable water.


With over 10,000 cases of backflow contamination reported annually, it’s critical to have your backflow preventers in Calgary tested on a yearly basis.


6 Steps to Test Your Backflow Device

Thousands of businesses and homeowners rely on Commercial Mechanical’s licensed plumbers for backflow testing in Calgary, but did you know that you can also do the testing yourself?


Although rather expensive, you can purchase or rent backflow testing kits from your local plumbing or building supply store. Besides your kit, have a wrench, water pressure gauge, and screwdriver nearby.

  1. Shut off the water supply. Warn others in your home not to use any water until the testing is complete and water pressure is back to normal.
  2. Inspect water direction. Whether you have a reduced pressure principal or double check valve device, the water should only flow in one direction according to the arrows or description indicated on the device.
  3. Clean and number test cocks. The test cocks and bushings should be free of dirt, dust, and debris. Make sure you have the number of test cocks and bushings needed for your device and number them for future reference.
  4. Examine shut-off valve. Close the number two shut-off valve. Wait several minutes, then hook up your test kit hoses. If a foul odor is present, your backflow preventer will need servicing before you continue any further.
  5. Follow test kit instructions. If there is no foul odor, go ahead with the test kit. Follow the instructions for your device and local by-law requirements.
  6. Turn water back on. Turn the water back on and run a few taps. Water should run backwards through the system. Keep an eye on the relief valve. If it opens, it may need to be replaced. Using your gauge, check the water pressure in the valve. If it rises as it flows backwards, the valve should be inspected by a professional plumber.


Avoid Major Health Risks, Contact the Professionals

If you need help with backflow testing, you can rely on Calgary’s plumbing experts at Commercial Mechanical.


As a top-rated plumbing company in Calgary, we are well equipped to ensure there is no cross-contamination on your property and your backflow devices are working properly. With summer well on its way, now is the time to test your backflow devices. Book your appointment today!