How to Choose the Right Backflow Preventer for Your Plumbing System

April 19, 2025

When it comes to keeping your drinking water safe and your plumbing system up to code, there is one small but crucial device that plays a significant role. Many homes and businesses have backflow preventers in San Diego, and regulations require these devices in many other spaces as well. A backflow preventer is an unsung hero in the plumbing industry, protecting your water supply from contamination, and protecting the public water supply, too.

But when it comes to these devices, there are several different options out there. So how do you choose the right one and make sure it’s right for your plumbing system? The best thing to do is work with a professional and discuss the needs with them. They will be able to make a recommendation. This guide helps you better understand the different choices available so you can make a fully informed decision.

What is a Backflow Preventer, and Why Is It Important?

A backflow preventer installs directly into the plumbing system. This device helps prevent backflow, which means it prevents any contaminated water from flowing the wrong direction and getting into a clean water supply. For example, when you flush the toilet, that is contaminated water that needs to only flow with wastewater. The backflow prevention device ensures this happens and prevents incorrect flow.

A backflow preventer does not just impact your immediate location, but it also protects public water supply. If backflow occurs at your property, it can also get into public clean water lines, which is a major contamination hazard. Backflow is most likely to occur when there is an issue like a blockage or when something like a main break, burst pipe, or heavy usage phenomenon happens.

The backflow preventer has one job and it is to make sure harmful substances and contaminants do not infiltrate the clean water system. These contaminants can include waste, but they also include things like chemicals, fertilizers, and pesticides, too. The last thing you want is for those to get into the drinking water.

In San Diego, the code requires backwater preventers for many facilities and some residential circumstances, too. This is not uncommon across the board, so it’s important to know your options and be proactive with testing.

Common Types of Backflow Preventers

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There are several different types of backflow preventers and they all work for unique scenarios or needs. The type that you choose is going to depend on the level of hazard as well as the design of your plumbing system. Let’s chat about some of the most common choices.

1. Atmospheric Vacuum Breaker

The atmospheric vacuum breaker, also known as AVB, uses air pressure to prevent siphoning of water. This particular option is most commonly used for hose bibs or lawn irrigation systems because of the unique air pressure design. It’s not a good choice when continuous pressure is part of the setup, which is why it’s primarily installed on systems that are not used all the time.

The AVB is affordable and easy to install, but you must install it downstream from a shutoff valve, and it does have certain limitations.

2. Pressure Vacuum Breaker

A pressure vacuum breaker, or PVB, uses a check valve and an air inlet valve to prevent back siphoning of water under pressure. These are easy to test and maintain, but they are most popular for sprinkler and irrigation systems. They do require regular testing because of the design, and you must install them above ground.

3. Double Check Valve Assembly

A double check valve assembly, or DCVA, works with two independent operating check valves that work together on one single assembly. They are compact for use indoors or outdoors, making them a popular choice for commercial and residential applications that have low-hazard concerns. These are not approved for use in any high-hazard scenario.

4. Reduced Pressure Zone Assembly

A reduced pressure zone assembly, which is also called RPBA or RPZ, uses two check valves with a relief valve between them. When the pressure drops, the relief valve opens to discharge any contaminated water, acting as a fail safe. Many industrial systems and high hazard commercial systems use this, and it’s one of the best choices for any serious contamination risk. It is a more expensive system that requires professional installation and testing.

Choosing the Right Backflow Preventer

When it comes to choosing a device, it’s always good to work with a professional. You don’t want to overpay for a system that is far more than you will ever need. However, you also don’t want to choose a system that isn’t capable enough for your needs and won’t work for your requirements.

Let’s talk about some things you should consider.

What Type of Plumbing System Do You Have?

This is going to be one of your first and most important questions. What kind of plumbing system are you protecting? If you simply are working with an irrigation system, you can likely get away with the simplest system. However, if you have a fire sprinkler system or you are in a facility that is connected to chemicals and pressurized equipment, you are likely going to need an RPZ.

What are Code Requirements?

San Diego requires many facilities to have backflow preventers, and there may be guidelines for the type you use as well. Check out the local code requirements as they pertain to your setup and use this to help choose a device.

Professional Testing or Maintenance Required?

Some devices require regular testing and maintenance, while others are sufficient. Some locations also require testing if you have any type of backflow device in place, so know the rules to comply with.

Work with One Stop Backflow Supply for Backflow Preventers in San Diego

If you’re in the San Diego area and looking for the right backflow device, we can help. One Stop Backflow Supply has a variety of options and can lend our expertise to help you choose the solution to best meet your needs. We work with many quality brands and solutions to meet every need.