Types of Backflow Preventers

Ever think about what’s flowing back into your water supply? When backflow happens, contaminated water can sneak into your clean water lines, bringing along bacteria, chemicals, or even sewage. That’s where backflow preventers come in. These essential backflow devices are built to stop that dirty reversal and keep your water safe. 

Without proper backflow prevention, you’re looking at potential health risks, costly plumbing repairs, and maybe even fines. It’s crucial to know which type of preventer fits your setup, how backflow testing works, and why proper backflow device installation matters for safety and compliance.

Importance of Backflow Prevention

What is Backflow?

Backflow is the unwanted reverse flow of water in your plumbing system. Instead of clean water flowing out of your faucet, dirty water could flow back in, bringing whatever it touched along the way.

What Can Go Wrong?

Backflow can seriously mess with your health and safety. We’re talking about the potential for waterborne diseases, which the CDC says lead to around 7.15 million illnesses a year in the U.S., along with 601,000 ER visits, 118,000 hospital stays, and over 6,600 deaths, costing more than $3.33 billion in healthcare expenses annually

Here are some warning signs of a backflow problem:

• Discolored or foul-smelling water
• Gurgling drains or bubbling toilets
• Water leaks or slow drainage
• Unusual taste in your drinking water

That’s why having backflow preventers in place matters. They keep contaminated water out of your drinking water. And staying on top of backflow prevention with proper backflow testing and timely repairs doesn’t just protect your home—it protects your health, your neighbors, and the environment.

Types of Backflow Preventers

Backflow preventers are installed at cross-connection points—spots where clean water can potentially come into contact with used or contaminated water. You’ll find these setups in residential plumbing, lawn irrigation, commercial systems, and industrial processes. Not every system needs the same kind of device, so it’s important to choose one that fits your environment and risk level.

Air Gap

This is the simplest and most fail-safe method. It’s literally just a physical gap between your water source and the receiving container, like the space between a faucet and a sink.

• Best For: Dishwashers, water softeners
• Pros: No moving parts means minimal maintenance
• Cons: Not suitable for pressurized systems

Atmospheric Vacuum Breaker (AVB)

This device introduces air into the system to break any potential siphon. It shuts off when water stops flowing.

• Best For: Outdoor irrigation, single-zone outdoor applications
• Limitations: Can’t be used in systems with continuous pressure
• Residential use: Garden hose bibbs, lawn sprinklers

Pressure Vacuum Breaker (PVB)

Unlike AVBs, these can handle continuous pressure. They include a spring-loaded check valve and an air inlet valve.

• Best For: Residential sprinkler systems
• Pros: Testable and approved for higher-risk areas
• Maintenance: Needs periodic inspection and testing

Double Check Valve Assembly (DCVA)

This one features two check valves in a row for added protection.

• Best For: Low-risk commercial buildings, fire sprinkler systems
• Pros: Easy to test and repair
• Limitations: Not recommended for high-hazard environments

Reduced Pressure Zone Device (RPZ)

This is the heavy hitter. It’s got two check valves and a relief valve between them, offering the highest level of protection.

• Best For: Chemical facilities, commercial kitchens, homes with fertilizer systems or booster pumps
• Pros: Required for high-hazard areas
• Cons: Needs annual backflow testing

Spill-Resistant Vacuum Breaker (SVB)

Similar to a PVB, but designed to avoid water spilling during operation.

• Best For: Indoor irrigation or where spillage could cause damage
• Pros: Great for tight, indoor spaces

Hose Bibb Vacuum Breaker

These screw onto your outdoor faucet and stop backflow through hoses.

• Best For: Garden hoses, outdoor water fixtures
• Pros: Affordable, simple to install, highly effective for everyday use

How to Choose the Right Backflow Prevention Devices

Not all backflow preventers are created equal. The one that works best for you depends on what you’re using it for and how risky the contamination could be. Here’s how to make the right choice:

Hazard Level

• Low-hazard systems (like basic irrigation) work with AVBs or DCVAs.
• High-hazard setups (involving chemicals or waste) need RPZs or PVBs.

System Pressure Requirements

• Make sure your device matches the pressure of your water supply.
• For systems with booster pumps or variable pressure, RPZs are the go-to.

Type of Application

• Sprinkler systems: AVB or PVB
• Swimming pools: RPZ or DCVA
• Drinking Water Supply: Always use an RPZ if contamination is possible
• Fire Systems: DCVA, unless antifreeze is involved—then go RPZ

Indoor vs. Outdoor Use

• AVBs and SVBs are best for outdoor or temporary setups.
• RPZs work well indoors but need proper drainage in case they discharge.

Budget & Maintenance Needs

• Hose bibb breakers are cheap and easy for basic protection.
• RPZs cost more but offer high-hazard protection.
• All testable devices require annual testing and certification.

The Role of Backflow Testing

Backflow testing is how you make sure your preventers are actually doing their job. Over time, parts can wear out or fail, and that’s when your water supply is at risk. Certified plumbers use specialized testing kits to verify that your system is safe and functional.

In New Mexico, the New Mexico Environment Department (NMED) requires annual testing for many backflow prevention devices. These rules exist to protect our drinking water, so staying compliant is just as important as keeping your family safe.

Signs you might need testing:

• You notice water smells off or looks discolored
• Your water pressure drops
• You find unexpected leaks near your device

Cost to test: Typically between $75–$250, depending on the type and setup.

Backflow issues don’t fix themselves. If it’s been a while since your last check—or if you’ve never had one—it’s time to schedule a test or talk to a pro about installing the right backflow prevention device. Clean water, peace of mind, and code compliance? Totally worth it.

Protect Your Water: Expert Backflow Device Installation Services

With over 60 years of experience, Steward’s Plumbing has helped homeowners and businesses install the right backflow devices and keep them running smoothly. Our certified technicians and licensed backflow testers design and install systems that meet all local codes and regulations. We use efficient, water-saving devices that are built to last, and we don’t just install and leave—we’re committed to long-term service and customer satisfaction.

Need help choosing the right setup for your property? We offer consultations to match you with the best system for your environment. Call us at 505-578-1540 or contact us online for expert advice.