Underground lawn and landscape irrigation systems present a continuous cross-connection hazard: sprinkler heads submerged in puddles or fertilized soil can siphon pesticides, animal feces, and chemical fertilizers back into residential drinking water during supply pressure drops. Western North Carolina water authorities require dedicated backflow prevention—either Pressure Vacuum Breakers (PVB) or Reduced Pressure Zone (RPZ) assemblies—tested annually before spring startup and properly winterized before mountain freeze events.
PVB assemblies (ASSE 1020) protect against backsiphonage and must be installed at least 12 inches higher than the highest downstream sprinkler head. We test the air inlet valve opening threshold (minimum 1.0 PSI above atmosphere) and verify check valve tightness under static head.
If an irrigation system incorporates fertilizer injection, chemical fertigation, or auxiliary lake/well backup sources, North Carolina plumbing code mandates an RPZ assembly instead of a PVB. We verify hazard classification and test compliance for private estates and commercial golf courses.
Mountain winter temperatures in WNC regularly plummet below 15°F, freezing and shattering exposed brass backflow bodies and plastic valve poppets. We utilize commercial high-CFM tow-behind air compressors to evacuate all water from backflow assemblies, main lines, and sprinkler manifolds.
When restoring irrigation service in April and May, we re-pressurize the system gradually, inspect for winter frost fractures, test the backflow assembly for immediate municipal certification, and submit documentation to your local water utility.
Our technicians arrive with calibrated 5-valve test equipment and file your official compliance report directly with your municipal water purveyor.
Schedule Same-Day / Priority InspectionBrass backflow valves retain trapped water in internal check valve pockets and bonnet chambers even when the main shutoff is closed. Unless blown out with high-volume compressed air and left with ball valves at a 45-degree angle, freezing water expands with over 30,000 PSI of hydraulic force, splitting the cast brass body.
Only if the PVB can be positioned at least 12 inches above the highest sprinkler head on the property. On steep mountain slopes, the highest head may be 30 or 40 feet uphill from the water meter; in these cases, a Reduced Pressure Zone (RPZ) assembly installed at the meter is legally required.
The best time is during your spring irrigation startup (typically April or May), allowing our technicians to inspect, test, and certify the assembly as soon as water service is restored.