Most cities in the US require yearly backflow testing. This is to be performed by a certified licensed tester who is registered and approved by the city they are testing in.

A failing backflow device puts you at risk of contaminating the water supply with tainted water or deadly chemicals and pesticides. During testing, a calibrated machine is hooked up to the backflow device and pressurized readings are evaluated and recorded. This routine maintenance ensures that the integrity of the backflow device is up to the safety standards set in place, and backsiphonage will not occur.