Backflow Prevention Testing is necessary in keeping your home sanitary. Backflow is the undesirable reversal in the flow of water from a real or potential source of contamination back to the potable (or clean) water supply. Consider having a garden hose in a bucket of soapy water at your home, and having backflow event occur causing that soapy water to “backflow” into the drinking water portion of your home. Various types of backflow preventers exist for different applications and health hazard conditions. The most common are reduced pressure backflow preventers and double check backflow preventers valves. Backflow preventers are primarily used in sewer, wastewater, residential, sprinkler and irrigation to prevent backflow situations.