It is a legal requirement for all backflow prevention devices (rated for high or medium hazard installations and testable fire service single check valves) to be tested during and after installation by a licensed plumber who is endorsed for backflow prevention testing. This test must also occur in 12 month intervals once installed.
Backflow occurs when water flows backwards from the drainage system into the water supply system. This water has the potential to carry contaminants that can harm the health of your household and community. Backflow is more likely to occur if: there’s a drop in pressure in the main, eg during a main break or water