Every year, thousands of homes experience water contamination due to backflow incidents that could have been prevented. Whether it’s from lawn chemicals, sewage, or industrial waste, the threat to your home’s drinking water is real.
A backflow preventer is a critical plumbing device that protects your home’s drinking water from contamination by preventing water from flowing backward into the potable supply. These devices are your first line of defense against dangerous contaminants like pesticides, sewage, and chemicals entering your family’s water.
Understanding backflow prevention is essential for Texas homeowners, where state regulations require specific protections and annual testing for many systems.
In this guide, we’ll cover everything from how backflow preventers work to Texas code requirements and installation considerations.
What is Backflow?
Backflow is the unwanted reverse flow of water—or other substances—into your home’s clean water supply. It happens when pressure changes in your plumbing system cause water to flow in the wrong direction.
There are two main causes:
- Back siphonage occurs when water pressure in the supply line drops suddenly, pulling contaminants into the system (think: a garden hose submerged in a pool).
- Back pressure happens when water pressure from a non-potable source becomes higher than the pressure in the potable system, forcing contaminants backward.
The risks are serious. Pesticides from lawn irrigation, bacteria from sewage, or chemicals from nearby commercial buildings can all make their way into your home’s drinking water during a backflow event.
Real-world examples include:
- Irrigation systems where fertilizer and herbicides can siphon back into the water line.
- Fire sprinkler systems that may contain stagnant or chemically-treated water.
What Does a Backflow Preventer Do?
A backflow preventer is a safety device that protects your home’s drinking water by making sure water flows only in one direction—into your plumbing system, never backward.
If backflow occurs (as explained above), this device stops contaminated water from re-entering your clean water supply. It’s your home’s best defense against pollutants like fertilizers, pesticides, or wastewater entering through cross-connections.
Backflow preventers are commonly required in any system where drinking water could come into contact with contaminants. Typical applications include:
- Residential irrigation systems, especially those with automatic sprinklers or fertilization systems
- Hose bibs where garden hoses could back-siphon dirty water
- Fire sprinkler systems with stagnant or chemically treated water
- Commercial kitchens using chemical dishwashers or detergent dispensers
- Industrial setups involving pressure systems or hazardous materials
Without a backflow preventer, any drop or change in pressure can allow pollutants to backflow into the water your family uses every day.
Types of Backflow Prevention Devices
There’s no one-size-fits-all device. Here’s a breakdown of the most common types of backflow preventers and how they work:
Air Gaps
This is the simplest form of protection. An air gap is a physical space—usually at least twice the diameter of the water outlet—between a water source and potential contamination.
Common uses: Sinks, dishwashers, and water softeners.
Atmospheric Vacuum Breakers (AVB)
AVBs prevent back siphonage by allowing air into the system if a vacuum is detected. They’re installed downstream of shutoff valves and must be placed above the highest point of water use.
Common uses: Hose connections, sprinkler systems.
Pressure Vacuum Breakers (PVB)
PVBs use a spring-loaded poppet and a vacuum relief valve to stop back siphonage. They’re suitable for higher-risk applications and require installation at least 12 inches above the highest outlet.
Common uses: Lawn irrigation systems.
Double Check Valve Assemblies (DCVA)
These have two check valves for extra protection. They’re ideal for low to medium hazard situations and offer a compact design that’s easy to test and maintain.
Common uses: Fire sprinkler systems, boiler feed lines.
Reduced Pressure Zone Devices (RPZ)
RPZs offer the highest level of protection. They use two check valves with a pressure-monitored relief valve in between. If either check fails, the relief valve opens to discharge contaminated water.
Common uses: Hospitals, chemical plants, or any place where contaminants pose a high health risk.
How Does a Backflow Preventer Work?
Backflow preventers use a combination of check valves, air inlets, and relief valves to control water flow. These components are designed to shut off or divert flow if water tries to move in the wrong direction.
- Check valves only allow one-way flow.
- Air inlets or vacuum breakers let air in to break the vacuum that causes siphonage.
- Relief valves open to discharge contaminated water when pressure imbalances are detected.
If pressure from a non-potable source builds up—or if supply pressure drops—these internal mechanisms kick in to keep contaminants out of your water supply.
Is a Backflow Preventer Required by Code in Texas?
Yes. In Texas, many homes and businesses are required by law to have a backflow preventer—especially if there’s a risk of water contamination from systems like irrigation, fire sprinklers, or auxiliary water sources.
The Texas Commission on Environmental Quality (TCEQ) enforces these rules under 30 TAC §290.44, which was most recently updated in 2023. It mandates that certain systems must have approved backflow prevention assemblies installed and tested annually by a licensed Backflow Prevention Assembly Tester (BPAT).
You’re likely required to have a backflow preventer if:
- You have an irrigation system with fertilizer injection
- You use a fire sprinkler system connected to city water
- Your home has a private well or alternative water source tied into the main supply
Failing to meet these requirements can result in fines, service disconnection, or code violations—especially in cities like Fort Worth, Plano, and Houston, where enforcement is strict.
Not sure if your system qualifies? Bacon Plumbing Heating Air Electric can help you stay compliant with inspections, testing, and certified installations.
How to Install a Backflow Preventer
Backflow preventers must be installed by a licensed plumber. This isn’t a DIY project—Texas plumbing codes require professional installation and certified testing to stay compliant and protect your drinking water.
A plumber will start by identifying any cross-connections—places where dirty water could mix with your clean water. Based on the risk level, they’ll recommend the right type of backflow prevention device.
Professional installation includes:
- Selecting the correct device for your system
- Installing it in the proper location and orientation
- Ensuring enough clearance for future inspections and testing
If you’re not sure what your home needs, Bacon Plumbing Heating Air Electric can handle everything—from inspection and installation to testing and paperwork.
What Does a Backflow Preventer Look Like?
Backflow preventers vary in size and appearance depending on the type. Common features include:
- Brass or stainless steel body
- Inlet and outlet shutoff valves
- Test cocks for pressure readings
- Relief valves (on RPZs)
You’ll usually find them near outdoor spigots, irrigation system connections, or where the main water line enters your home. Some are installed above ground in insulated boxes to protect from freezing.
Maintenance and Testing of Backflow Preventers
Routine maintenance is critical to keep your backflow preventer working properly. Texas regulations require annual testing for many devices, especially RPZs and PVBs.
Watch for signs of trouble:
- Visible leaks
- Sudden pressure drops
- Discolored water
Only licensed testers can perform official inspections. After testing, you’ll receive documentation for code compliance—which may be required by your water provider or city.
Keep records of all inspections and repairs in case of future issues or audits.
Protect Your Drinking Water with Backflow Prevention
Backflow happens when contaminated water flows in the wrong direction back into your clean water supply. It can be caused by sudden changes in water pressure, such as during a water main break or when firefighters tap into a hydrant. That’s where a backflow preventer comes in. This device keeps your drinking water safe by preventing dirty or hazardous water from mixing with the clean water in your home.
Texas law requires annual testing of all backflow prevention assemblies. Failing to test or maintain your device could result in serious health risks and fines.
At Bacon Plumbing Heating Air Electric, we’re licensed experts in backflow preventer testing, installation, and maintenance. Whether you’re scheduling your routine inspection or need fast repairs, we’re ready to help—24/7, with real people answering the phones.
- Stay compliant with local water safety codes
- Protect your home and family from potential water contamination
- Get fast, same-day service with upfront pricing
Need your annual inspection? Call us today at (469) 213-6505 to schedule your backflow preventer test. Or book online for easy scheduling at your convenience.
