Backflow occurs when water flows backwards from your property into the mains supply, contaminating public drinking water.
Caused by back pressure or back siphonage during mains pressure drops.
Device types: RPZD for high hazard $500-$1,500, DCVA for medium hazard $300-$800, dual check valve for low hazard $50-$150, air gaps.
Annual testing required for testable devices by accredited plumber at $100-$200 per device.
Required for properties with pools, irrigation, rainwater tanks, commercial kitchens, or booster pumps..