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Backflow happens when dirty water reverses direction and flows back into your clean water lines. You prevent it by removing cross-connections, installing the right backflow preventer at every risk point, and having that device tested on schedule. An air gap is the strongest protection, and a tested assembly is the next best thing. If you need help, our backflow prevention and testing team covers the Triad.
Key Takeaways
- Backflow has two causes. Back-pressure pushes water backward, and back-siphonage pulls it backward when supply pressure drops.
- Irrigation systems are the most common risk at a house, because sprinkler heads sit in soil, fertilizer and pet waste.
- An air gap beats every mechanical device, since there is no moving part to fail.
- High Point requires testing. Domestic, irrigation and fire suppression devices all have to be inspected and maintained on a regular schedule.
- Only a certified tester counts. A homeowner cannot self-certify a backflow assembly, and results have to be filed with the city.
What Is Plumbing Backflow, and Why Does It Happen?
Plumbing backflow is water flowing the wrong way through your pipes. Instead of clean water moving from the city main into your house, contaminated water moves from your property back toward the main, or back into the fixtures your family drinks from.
Your plumbing keeps water moving in one direction using pressure. When that pressure balance breaks, gravity and physics take over and water finds the path of least resistance. That path can run backward.
Back-Pressure and Back-Siphonage Are Not the Same Problem
Back-pressure happens when the pressure on your side of the system climbs higher than the pressure in the supply line. A boiler, a pump, a pressure washer or a heated recirculating loop can all do this. The higher pressure shoves your water back into the main.
Back-siphonage is the opposite. Supply pressure drops suddenly, usually because a water main breaks, a hydrant is opened hard, or a large fire line is charged nearby. The vacuum that follows sucks water backward through any open connection.
The types of backflow preventers on the market exist because those two problems need different hardware. A device rated for siphonage only will not stop back-pressure.
Where Backflow Starts in Most Triad Properties
A cross-connection is any point where drinking water can touch something that is not drinking water. Most homes have several and the owner has no idea. Guilford and Forsyth County properties with irrigation, older additions or workshop plumbing tend to have the most.
These are the connections we find most often on service calls across High Point, Greensboro and Winston-Salem:
- Irrigation systems. Sprinkler heads sit at ground level in soil, fertilizer and runoff.
- Hose bibs with a hose left in a bucket, a pool, a pet bowl or a mop sink.
- Boilers and hydronic heat, which carry treated water that should never mix with tap water.
- Fire suppression lines, where water sits stagnant in the pipe for years.
- Commercial kitchen equipment, soda machines, dish machines and grease traps.
- Chemical injectors and well systems tied into a public water connection.
A hose left sitting in a bucket of driveway cleaner is the classic example. If the main breaks down the street while that hose is submerged, the cleaner gets pulled straight into the house.
How to Prevent Plumbing Backflow: Six Steps That Work
Prevention is mostly about removing the connection, and where you cannot remove it, controlling it with the right device. Here is the order we work through on a property.
- Walk the property and list every cross-connection. Include irrigation, hose bibs, mechanical rooms, outbuildings and anything added after the original build.
- Remove what you can. A hose pulled out of a bucket is a cross-connection that no longer exists. Free, and permanent.
- Add an air gap wherever the design allows. A physical gap between the tap and the flood level of the fixture cannot fail mechanically.
- Install vacuum breakers on every hose bib. These cost a few dollars each and handle the single most common household risk.
- Put a tested assembly on irrigation, boilers and fire lines. The device type depends on how hazardous the connection is, and that call needs a licensed plumber.
- Test annually and keep the paperwork. A failed device looks identical to a working one from the outside.
Most homeowners can handle steps one, two and four themselves. Steps three and five involve the potable supply and are permit work in North Carolina. Call All Star Plumbing at (336) 462-1080 and we will walk the property with you before anything gets installed.
Which Backflow Preventer Do You Need?
Device choice comes down to hazard level and whether back-pressure is possible. A low hazard makes water unpleasant. A high hazard makes it dangerous.
| Device | Protects Against | Hazard Level | Typical Use |
|---|---|---|---|
| Air gap | Both | High | Sinks, tanks, drain lines |
| Hose bib vacuum breaker | Back-siphonage | Low to moderate | Outdoor spigots |
| Pressure vacuum breaker (PVB) | Back-siphonage | Moderate | Residential irrigation |
| Double check valve assembly (DCVA) | Both | Low | Fire lines, some irrigation |
| Reduced pressure zone (RPZ) | Both | High | Boilers, chemical feeds, commercial |
An RPZ is the heavy hitter and it is what most commercial properties end up with. It also needs a drain, because it dumps water when it relieves. Putting one in a finished basement without planning that drain is a mistake we get called to fix.
What High Point and Winston-Salem Actually Require
This is where most property owners get caught out. Installing a device is not the end of the job. The city wants proof it still works.
The city’s published High Point backflow rules state that all backflow devices in the city are required by the adopted North Carolina Plumbing Code to be inspected, tested and maintained at regular intervals. That covers domestic systems, irrigation systems and fire suppression systems. Test results are submitted electronically, and only approved testers can file them.
Winston-Salem runs its own program with the same core idea. The Winston-Salem backflow program page lists who is covered and how testing is handled there. If you own property in both cities, do not assume one set of paperwork satisfies the other.
Miss the testing window and the usual result is a notice, then a deadline, then a service interruption. None of that is expensive to avoid. It just has to be on somebody’s calendar.
Backflow Questions Triad Homeowners Ask
Does every house need a backflow preventer?
No. A house with no irrigation, no boiler and no chemical connection may only need vacuum breakers on its hose bibs. Add an irrigation system, a pool fill line, a boiler or a well tied to city water, and a tested assembly becomes required. The connection creates the requirement, not the house.
How do I know if I have a backflow preventer in my house?
Look where the water line enters the building and at your irrigation manifold. A backflow assembly is usually brass or bronze, sits above ground, and has two small test ports with screw caps plus two shutoff valves. Hose bib vacuum breakers are the small brass caps screwed onto outdoor spigots.
Do you need a plumber to install a backflow preventer?
For anything beyond a hose bib vacuum breaker, yes. Cutting into the potable supply to fit a PVB, DCVA or RPZ is licensed work in North Carolina, usually requires a permit, and the device has to be tested and certified after installation before the city accepts it.
What happens if a backflow preventer fails?
Failure is usually silent. A fouled check valve or a worn relief seat keeps the device looking normal while it no longer stops reverse flow. An RPZ often gives one visible clue, which is water discharging from the relief port. That is why scheduled testing exists.
Can backflow make you sick?
It can. Backflow incidents have moved fertilizer, pesticides, boiler chemicals and sewage into drinking water lines. Symptoms usually show up as sudden stomach illness across a household, often alongside water that tastes, smells or looks wrong. Stop drinking it and call a licensed plumber the same day.
Get Your Backflow Device Tested Before the City Asks
If you have an irrigation system, a boiler, a fire line or a commercial water connection anywhere in the Triad, the device protecting it needs a current test on file. If you are not sure whether you have one, that is worth an hour of a plumber’s time.
Call All Star Plumbing at (336) 462-1080 and we will locate your device, test it, repair or replace it if it fails, and file the paperwork. A real person answers the phone 24 hours a day, and you get upfront pricing before any work starts. If you turn the quote down, you owe nothing. You can also schedule a backflow test online.
Family owned in High Point since 2007, licensed, bonded and insured, and serving 22 communities across Guilford, Forsyth and Davidson counties. We also handle water quality testing services if your water already looks or tastes wrong, and 24 hour sewer backup emergency help when contamination has already reached the house. Greensboro property owners can start at our plumber in Greensboro page.
All Star Plumbing
4003 North Main Street
High Point, NC 27265
Phone: (336) 462-1080
Hours: Open 24 hours, 7 days a week
NC Plumbing License #15130
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