Which Plumbing Device Helps Prevent A Backflow?

Last Updated On August 8, 2022
which plumbing device helps prevent a backflow

Plumbing backflow can impact your clean water supply, so it is important to take steps to prevent it from happening in the first place. One of the best ways to do this is by installing a plumbing device called a backflow preventer

But which backflow preventer is right for your home or building? In this blog post, we will discuss the different types of backflow preventers and help you decide which one is best for you!

In this PlumbingNav guide, we will cover:

  • What is backflow in plumbing?
  • Different types of backflow preventers
  • Review of the 5 best backflow preventers

ImageProduct
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Wilkins 1-975XL2 Backflow Preventer
  • Made from solid bronze
  • Designed for potable drinking systems
  • Easy to replace
  • Made from solid bronze
  • Designed for potable drinking systems
  • Easy to replace
View on Amazon
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Watts Brass & Tubular #9D-M3 1/2 1/2″ Backflow Preventer
  • Can withstand up to 212 degrees
  • Inexpensive
  • Easy to install
  • Can withstand up to 212 degrees
  • Inexpensive
  • Easy to install
View on Amazon
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Zurn Wilkins 2″ 350XL Double Check Backflow Preventer
  • Made from copper
  • Removable plastic cover for easy repair
  • Can be installed vertically
  • Made from copper
  • Removable plastic cover for easy repair
  • Can be installed vertically
View on Amazon
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Febco 825EBV 825Y Quarter Turn Reduced Pressure Zone Assembly, 1″
  • meets all specifications of AWWA, ASSE, CSA
  • Inline serviceable parts make it easy to maintain 
  • lead-free
  • meets all specifications of AWWA, ASSE, CSA
  • Inline serviceable parts make it easy to maintain 
  • lead-free
View on Amazon
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Zurn 1-950XLT Wilkins Top Access Double Check Valve 1-Inch Backflow Preventer
  • Top access design easy to operate and maintain
  • Compatible with vertical installation
  • Inexpensive
  • Top access design easy to operate and maintain
  • Compatible with vertical installation
  • Inexpensive
View on Amazon

Our Overall #1 Rated Pick

Updated On August 8, 2022

Our #1 Rated Pick: Wilkins 1-975XL2 Backflow Preventer

The bronze Wilkins 1-975XL2 1” vacuum breaker prevents back-siphonage and back-pressure, extending the life of your pipes by up to 20%! It uses a wye pattern design for short lay length, reducing labor costs during replacement. 

Review of The Best Backflow Preventers

What's In This Guide?

      What Is A Backflow, Anyway?

      Backflow is when water or other liquids flow backward or “back into” your home through the plumbing system. In other words, what you’re trying to send out heads in reverse.

      In many cases, the backflow contains unsanitary wastewater or water treated with chemicals. See, many of the pipes in your home come together at a certain point, including pipes related to air conditioning and your home’s outdoor irrigation system and sprinkler system. 

      Unfortunately, improper pressure levels or installation angles can send the contaminants of those pipes back into your home.

      Even if your public water system provides quality freshwater, backflow can find its way into your water line and negatively impact the water quality. Chemicals can also get in the air and affect your indoor air quality.

      A faulty backflow prevention program can also cause water damage to your home and damage to your pipes, including corrosion and leaks

      What Causes Plumbing Backflow?

      Backflow can happen for a variety of reasons, but it usually occurs when there is a sudden change in pressure in the pipes. Pressure fluctuations in the pipes can be caused by things like a pressure vacuum from elevated piping, or the weight of water in taller homes or high-rise buildings if a plumbing riser wasn’t properly installed.

      Backsiphonage refers to backflow caused by negative pressure. Back pressure refers to backflow caused by positive pressure.  This is why your plumbing system must be properly vented. This especially comes into play where vertical vents aren’t accessible, and where loop vent plumbing comes into play.

      Did You Know? A study of water contamination illnesses discovered more than 50% occurred as a result of backflow.

      did you know how to prevent a plumbing backflow - best plumbing devices

      What Causes Plumbing Backflow?

      Backflow can happen for a variety of reasons, but it usually occurs when there is a sudden change in pressure in the pipes. Pressure fluctuations in the pipes can be caused by things like a pressure vacuum from elevated piping, or the weight of water in taller homes or high-rise buildings if risers weren’t properly installed.

      Backsiphonage refers to backflow caused by negative pressure. Back pressure refers to backflow caused by positive pressure.  

      Did You Know? A study of water contamination illnesses discovered more than 50% occurred as a result of backflow.

      How to Prevent Backflow: 

      Spoiler alert, you can’t prevent backflow but the right device can. Backflow can cause serious damage to your home or health, so it is important to take steps to prevent backflow from happening in the first place.

      One of the best ways to do this is by installing a plumbing device called a backflow preventer. Which plumbing device helps prevent a backflow? We’ll explain the two main types below. 

      By the way…

      If you already have a backflow device in place, you should get regular backflow testing to ensure it’s working properly. An inspection will rate the effectiveness and proper functioning of your system. Don’t assume it’s working without testing it.

      What Are The Different Types Of Plumbing Devices That Can Prevent Backflow?

      There are two main types of backflow preventers: atmospheric vacuum breakers (AVBs) and double-check valve assemblies (DCVAs). 

      Both plumbing devices work to prevent backflows by creating a barrier that will allow water to flow in one direction only. Think of this as a mechanical air gap.

      An atmospheric vacuum breaker consists of the following components:

      • Inlet shutoff valve (at the bottom)
      • A single valve body
      • A check valve
      • Two test clocks
      • Outlet shutoff valve

      A double-check valve assembly consists of the following components:

      • An inlet shutoff valve
      • Valve body with two spring-loaded independently operated check valves
      • Four test valves
      • Outlet shutoff valves

      How do you know which plumbing device is best for you to prevent backflow?

      So, which type of backflow preventer is right for you? That depends on a few factors, including the location of the potential backflow and the water pressure in your home. 

      DCVBs are typically best for low-pressure systems, while AVBs can handle higher-pressure systems. However, DCVBs offer more installation flexibility.

      AVBs are typically installed on outdoor faucets and hose bibs, while DCVAs are installed on the main water line coming into your home. 

      If you’re not sure which type of backflow preventer is right for your home, talk to a professional plumber who offers backflow services.

      Best Backflow Preventer Reviews

      Now let’s explore our favorite units so you can decide on the perfect choice for your situation.

      Our #1 Rated Pick: Wilkins 1-975XL2 Backflow Preventer

      The bronze Wilkins 1-975XL2 1” vacuum breaker prevents back-siphonage and back-pressure, extending the life of your pipes by up to 20%! It uses a wye pattern design for short lay length, reducing labor costs during replacement. 

      Pros

      • Made from solid bronze
      • Designed for potable drinking systems
      • Easy to replace

      Cons

      • Expensive
      • No top access check design
      • Not lead-free

      Our #2 Rated Pick: Watts Brass & Tubular #9D-M3 1/2 1/2″ Backflow Preventer

      This ½” backflow preventer won’t break the bank, while still effectively preventing backflow in nonpotable situations, including boilers. It can withstand hot water up to 212 degrees, making it suitable for both residential and most commercial needs.

      Pros

      • Can withstand up to 212 degrees
      • Inexpensive
      • Easy to install

      Cons

      • Made from nonsolid brass
      • Not made for drinking water
      • Contains lead

      Our #3 Rated Pick: Zurn Wilkins 2″ 350XL Double Check Backflow Preventer

      When you need a product that will work for larger items and outdoor systems, you need this 2” double check valve assembly 350XL backflow preventer made in the US by Zurn Wilkins. It’s made from copper, making it especially durable. It also includes a drain off feature and can be installed vertically.

      Pros

      • Made from copper
      • Removable plastic cover for easy repair
      • Can be installed vertically

      Cons

      • Expensive
      • Heavy
      • May not adhere to code for indoor use

      Our #4 Rated Pick: Febco 825EBV 825Y Quarter Turn Reduced Pressure Zone Assembly, 1″

      This product is a reduced pressure zone assembly that automatically reduces the pressure between check valves to at least 5psi lower than the inlet pressure. This product is designed for non-potable water applications and operates under maximum working pressures of 175Psi and temperatures of 32 to 140 degrees F,  including test cocks.

      Pros

      • meets all specifications of AWWA, ASSE, CSA
      • Inline serviceable parts make it easy to maintain 
      • lead-free

      Cons

      • Only withstands 140 degrees (not suitable for some commercial and industrial needs)
      • Not made for potable water systems
      • Plastic relief valve

      Our #5 Rated Pick: Zurn 1-950XLT Wilkins Top Access Double Check Valve 1-Inch Backflow Preventer

      The Zurn 1-950XLT Wilkins Top Access Double Check Valve is a professional-grade backflow preventer that is easy to maintain and fits within standard meter boxes. It features nary replaceable seats and silicone rubber check disks, making it ENTIRELY serviceable in line. This tried and true design is favored by installers worldwide for its ease of use and reliability.

      Pros

      • Top access design easy to operate and maintain
      • Compatible with vertical installation
      • Inexpensive

      Cons

      • Can freeze if not protected
      • Not lead-free
      • Can’t use for potable water supply

      How to Install a Backflow Prevention Assembly

      A backflow preventer is a crucial component of any plumbing system, and it is important to install one correctly in order to avoid any issues down the line. Here are the steps to install a backflow preventer:

      Step One: Begin by shutting off the water supply to your home. This will ensure that there is no water flowing through the pipes while you are working.

      Step Two: Next, locate the main water line coming into your home. This is usually located near the water meter or where the water main enters your property.

      Step Three: Once you have located the main water line, cut it using a hacksaw or another type of saw. Be sure to leave enough room on either side of the cut so that you can install the backflow preventer.

      Step Four: Now, take the backflow preventer and install it according to the manufacturer’s instructions. Once it is in place, turn on the water supply and check for leaks. If there are no leaks, then you have successfully installed your backflow preventer!

      See the following video for more advice for installing backflow prevention devices:

      FAQ’s About Preventing Backflow In Plumbing

      What is the best way to prevent plumbing backflow?

      The best way to prevent backflow is with the help of a backflow preventer. Consider whether the backflow preventer is appropriate for your particular needs before you buy it. 

      What are 2 kinds of plumbing backflow prevention methods?

      The two types of backflow prevention methods are reduced pressure and double-check. Reduced pressure backflow devices work best on outdoor bibs, while double-check backflow preventers are more appropriate for interior applications. 

      What is the best back flow preventer?

      Choose from a residential or commercial plumbing device that is appropriate for your backflow situation. Read our reviews to decide what suits your needs. 

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      About Plumbing Navigator

      We write about "all things plumbing," helping you navigate common questions, repairs, and the best plumbing products on the market.

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      We write about “all things plumbing,” helping you navigate common questions, repairs, and the best plumbing products on the market.

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