Backflow FAQ

Backflow is the undesirable reverse flow of water back into the public supply. Normally water flows one way — from the main into your property — but a pressure change can reverse it and pull contaminated water backward into the clean supply everyone drinks.

Two things: backpressure, when downstream pressure exceeds the supply pressure, and backsiphonage, when negative pressure in the main (from a water-main break or a hydrant opening) siphons water backward.

The main types are the Reduced Pressure Zone (RPZ/RP) for high-hazard connections, the Double Check Valve (DCVA), the Pressure Vacuum Breaker (PVB) common on irrigation, and the Atmospheric Vacuum Breaker (AVB) for specific low-hazard uses.

A certified tester attaches calibrated gauges to the test cocks, briefly isolates the assembly, and verifies the check valves and relief valve hold pressure to spec. It is quick, non-destructive, and usually takes under an hour.

Yes. We test, repair, replace, and protect assemblies for homes, restaurants, medical and commercial properties, and irrigation systems across Chapel Hill and the Triangle.

Irrigation systems typically use a Pressure Vacuum Breaker (PVB) or, in some cases, an Atmospheric Vacuum Breaker (AVB), since fertilizer and lawn chemicals sitting in the line create an obvious hazard if water reverses. A home’s main water line more often uses a Double Check Valve Assembly (DCVA), or a Reduced Pressure Zone (RPZ) assembly for higher-hazard connections like a boiler or fire line. Which one applies to your property depends on the connection type and your water authority’s requirements — we’ll confirm the right assembly for your specific setup rather than assume.

Most water authorities keep their own record once a certified tester submits results, but policies vary, so it’s worth confirming with yours directly if you want to know their exact retention practice. On our end, we keep a copy of every test we perform and can resend it to you or your water authority if something gets lost.

Notices usually mean either your annual test is coming due, it’s overdue, or a new connection — like installed irrigation — needs an assembly added. The exact wording and process vary by water authority, so the most reliable next step is calling the number on the notice or reaching out to us — we can help you figure out what’s actually being asked and get it scheduled before it becomes a bigger issue.

The testing requirement itself comes from your water authority and NC plumbing code, not your insurance company. That said, a failed or missing backflow assembly that leads to contamination or water damage could affect a claim, so it’s worth keeping your testing current for more than one reason. For questions about your specific policy, your insurance agent is the right person to ask.

Fire lines are typically treated as a higher-hazard connection, often requiring a Reduced Pressure Zone (RPZ) assembly rather than the double-check valve common on a household line, and some jurisdictions add extra inspection steps because of the fire-suppression role. The annual testing cycle is generally similar across assembly types, but the specific rules depend on your local water authority and fire code — we can confirm what applies to your property.

It can. A home inspector may note a missing or clearly failed assembly, and some water authorities won’t transfer service, or will flag the account, if testing has lapsed. It’s worth checking the test status before closing rather than after, especially if the home has irrigation. We can test or bring a device up to date quickly if it’s part of a closing timeline.

Options can vary and change, so rather than give you an outdated answer, ask us directly when you call — we’ll tell you what’s currently available.

Testable assemblies — RPZ and double-check valves — have test cocks that let a certified tester check the check valves under pressure, and they’re required almost everywhere for irrigation and higher-hazard connections. Non-testable assemblies, like a simple atmospheric vacuum breaker, don’t have that capability and are only approved for specific low-hazard uses. If you’re not sure which one is on your property, send us a photo or let us take a look — we can identify it and tell you what your testing obligation actually is.

Testing itself can be done any time the device isn’t frozen or shut down for winter — it doesn’t require warm weather. That said, if your assembly is above ground and unprotected, we may recommend winterizing it (shutting it down and draining it) rather than testing it in the middle of a cold snap, since testing an already-vulnerable device in freezing temperatures isn’t worth the risk. We can talk through timing when we schedule.