It's also possible that your backflow preventer is near the main shutoff valve for your home. For a homeowner, the sewer backflow preventer usually will be above the ground, so you or your plumber ...

A big pipe carries waste from your house to the main sewer line under the street. If either becomes plugged or overloaded, ...

Close the valves and release any water by using a screwdriver to turn the test ports to release any water that is in the backflow preventer. For a visual, here’s a report from KHOU 11’s ...