Backflow preventers keep your drinking water clean. They stop dirty water from entering your water system. You need a backflow prevention device. This is important whether you have a home sprinkler system or a large irrigation setup.
Some stop both backpressure and backsiphonage. Others don’t. If you guess wrong, you might break the rules or worse, contaminate your potable water supply.
This article will cover everything there is to know about backflow preventer types. Let’s dig in…
Key Takeaways
- Backflow happens when water flows in the wrong direction.
- A backflow prevention device stops dirty water from entering your clean supply.
- Different types of backflow preventers work for different setups.
- AVBs and PVBs are common in lawn irrigation systems.
- RPZ assemblies are required in high-risk zones.
- DCVAs are good for low-hazard systems.
- Picking the wrong device can be a health hazard, and a code violation.
What Is Backflow and Why It Happens
Backflow happens when pressure in a water system shifts. This can cause contaminated water to reverse and enter the clean water line. It usually happens in two ways:
- Backsiphonage: A sudden drop in supply pressure pulls water backward.
- Backpressure: Higher pressure in the system forces dirty water into the clean line.
Both are bad news. Backflow prevention devices exist to stop this.
Types of Backflow Preventers and How They Work
Let’s break down the most common types. You’ll learn what they do, how they work, and where to use them.
Atmospheric Vacuum Breaker (AVB)
The AVB is a one-way valve that lets air in when pressure drops. It protects against backsiphonage only.
- Good for single-zone sprinkler systems.
- Must be installed above the highest outlet.
- Cannot be under constant pressure.
Pressure Vacuum Breaker (PVB)
The PVB is a step up from the AVB. It has a spring loaded check valve and air inlet valve. It can handle constant pressure.
- Works with irrigation systems that run on timers.
- Must be installed 12 inches above the highest outlet.
- Needs yearly testing.
Double Check Valve Assembly (DCVA)
This device has two check valves in series. It protects against both backpressure and backsiphonage, but only in low-risk situations.
- Ideal for lawn irrigation with no fertilizer injectors.
- Can be buried in a valve box.
- Requires annual testing in most cities.
Reduced Pressure Zone Assembly (RPZ)
The RPZ is the most protective option. It has two spring loaded check valves and a relief valve in between. If pressure shifts, it dumps contaminated water through the relief valve.
- Required for systems using chemicals or with cross-connections.
- Always installed above ground.
- Must be tested yearly.
Spill-Resistant Vacuum Breaker (SVB)
Like a PVB, but designed for indoor use. Has a sealed air inlet to prevent spills.
- Good for indoor irrigation systems.
- Not common, but code-approved in many cities.
Choosing the Right Backflow Prevention Device
Here’s a quick guide:
- For a basic sprinkler system: Use a PVB or AVB.
- For a system with fertilizer injection: Use an RPZ.
- For low-risk areas with no chemicals: A DCVA may be enough.
- For sinks or dishwashers: An air gap works best.
Check with your city before you install anything. Backflow preventers are often required by local code, and the wrong one could land you in hot water.
Lawn Sense No-Nonsense Advice: Protect Your Yard and Water Supply
If you’re installing or upgrading your irrigation system, don’t leave this to guesswork.
Lawn Sense means no nonsense and that includes how we handle your water system. We help homeowners in Dallas, TX and surrounding areas keep their lawns green, their backflows up to code, and their water safe. Call us before small problems turn into big issues.
FAQs
Do all sprinkler systems need a backflow preventer?
Yes. Most cities require one by law. Even if they didn’t, it’s the smart move.
What’s the difference between a PVB and a DCVA?
A PVB only protects against backsiphonage. A DCVA protects against both types of backflow. But only for low-risk systems.
Is an RPZ overkill for a home lawn system?
Sometimes. But if you’re using fertilizer injectors, or if city code says so, you’ll need one.
How often do I need to test my backflow prevention device?
Usually once a year. Some cities send notices. Others expect you to keep track.
Can I install my own backflow preventer?
Not always. Some cities require licensed pros. Even if they don’t, a bad install could void your insurance or lead to contamination.
Is an air gap better than a valve?
It’s the safest but not always practical. You can’t use an air gap in a pressurized irrigation system.
What happens if backflow occurs?
Contaminated water may enter your drinking water. That includes pesticides, fertilizer, and bacteria. Not worth the risk.
Final Thoughts: Don’t Skimp on Backflow Prevention
Picking the right backflow preventer keeps your family safe and your lawn thriving. AVBs and PVBs are great for most sprinkler systems.
DCVAs are fine for low-risk setups. RPZ assemblies are the heavy hitters. Use them when safety and code demand it.
Want help? Call Lawn Sense. We take the guesswork out of backflow protection.
Lawn Sense means no nonsense.