What is a Backflow Preventer and How Does it Work?

Have you ever heard of a backflow preventer but don’t know what it does or why it’s important? Well, you’ve come to the right place! In this blog, we’ll be explaining exactly what a backflow preventer is and how it works. So put on your thinking caps and get ready to learn all about backflow preventers!

Introduction to Backflow Prevention

Backflow preventers are important components of a plumbing system and help ensure that water is going in the right direction.

A backflow preventer is a valve that prevents contaminated or non-potable water from flowing backward into the system and contaminating the potable drinking water supply, thus ensuring public safety. Backflow prevention valves are required in many plumbing applications due to legal requirements, health standards or building codes.

There are several types of backflow preventer devices available on the market today, ranging from simple air gap fittings to sophisticated electrical and mechanical devices. The type of backflow prevention device you choose will depend on your specific application. Backflow preventers work by creating a barrier between your potable and nonpotable water sources; when the pressure decreases in one direction, the valve closes to preserve pressurization in the other direction and help ensure that no contaminated water can enter the drinking water supply. In most cases, this is accomplished with:

Air gap fitting or an isolation approach where two separate piping systems for each kind of fluid source are installed and segregated valves are employed to provide control over each system independently.

Types of Backflow Prevention

Backflow is defined as the flow of water from a lower-pressure plumbing system into a higher-pressure system. The most common cause of backflow is negative pressure in the higher-pressure system, but it can occur when there’s a sudden change in pressure or when valves are left open. When this happens, dangerous or contaminated materials can enter the higher-pressure system and contaminate drinking water supplies or other water sources.

Backflow prevention systems are designed to protect pipes and keep them free from contaminants. They come in two types – physical devices that block backflow and chemical devices that kill bacteria or other organisms entering through backflow. Some of the physical backflow prevention systems available include:

  • Double check valves
  • Reduced pressure zone assemblies
  • Air gaps
  • Vacuum breakers

Chemical devices usually employ chlorine tablets added to the incoming/outgoing water lines to eliminate bacteria as it passes through them.

Read in detail about: Backflow preventer vs Check valve

Benefits of Backflow Prevention

Backflow prevention is an essential part of protecting your home’s water supply. A backflow preventer, or BFP, helps to prevent contaminated or polluted water from entering your home’s potable water system. By preventing backflow, you can help protect the health and safety of both yourself and your family. The following are some of the key benefits that a backflow prevention device can provide:

  1. Health: One of the main benefits of having a backflow prevention device is that it can help to keep potentially harmful contaminants out of your home’s drinking water supply. By preventing cross connections and contamination, you can rest assured that the water in your home won’t be compromised by any outside sources.
  2. Safety: Another advantage is that it can also offer added protection from very hot temperatures in hot water tanks and other sources of high pressure or exposed high temperatures in pipes. This helps ensure that you won’t be exposed to scalding hot water when using faucets and showers in your house.
  3. Efficiency: Installing a backflow preventer can also help ensure better efficiency when it comes to piping systems in your home. Without one, there could be sudden surges in pressure or even disruptions from debris caught in plumbing lines which could require expensive repairs over time and lead to higher utility bills as a result.

By investing in a quality BFP for your home, you’ll be able to enjoy these benefits while ensuring everyone’s safety within its walls at all times!

Common Causes of Backflow

Backflow is the reverse flow of water, wastewater, or other liquids through a piping system that can contaminate the potable water supply. Unprotected potable-water systems can become compromised when there is a sudden drop in pressure due to high demand, electric power failure, or ruptured pipes.

Common causes of backflow include:

  • Cross-connection between potable and non-potable lines. This occurs when non-potable water is improperly connected to the clean drinking water supply.
  • Line breaks that create a gap between hot and cold water lines or pressurized and unpressurized areas.
  • Pressure surges from outside sources such as fire hydrants being used for firefighting activities or sewage pump failures in an upstream location.
  • Improperly operating valves, pumps or other mechanical devices that permit a reverse flow of liquid into another area beyond its intended use.

Backflow prevention devices are designed to reduce these risks by controlling the direction of fluid and preventing it from flowing backwards into the clean drinking water supply system. They come in several types and sizes that vary depending on their intended use and purpose, including air gaps, reduced pressure zone devices, double check valves, etc. Each type is specifically designed to provide reliable protection against bypassing irregularities in drinking water systems due to different circumstances and conditions.

Installation of Backflow Prevention

Backflow prevention devices are required for all water systems. They are designed to keep drinking water safe from contamination and can protect against backflow, back-siphonage, or cross-connection of the water supply. In order to ensure that the device is installed properly and can perform optimally, it is important to understand the installation process and what materials are needed.

When installing a backflow preventer:

  • Inspect existing piping if one was not previously installed
  • Determine size and type of backflow preventer
  • Install appropriate fittings
  • Shut off main water supply line
  • Cut pipe, connecting new device to nonpotable source and/or irrigation system
  • Test device manually or with pressurization devices for proper operation
  • Drain remaining system pressure

It is important that qualified personnel conduct the installation of any backflow preventer. Improperly configured or damaged components can lead to serious plumbing problems. A professional should carefully inspect installed units regularly to ensure their proper operation.

Testing and Maintenance of Backflow Prevention

Testing and maintenance of backflow prevention systems are required by national and local plumbing codes for all commercial, industrial, and fire sprinkler systems. Backflow preventers must be tested at least annually to ensure that they are working properly, as well as inspected to identify any potential issues. The National Fire Protection Association (NFPA) also recommends having a regular maintenance plan in place that includes cleaning or replacing parts as needed.

A backflow preventer works to prevent hazardous or polluted water from flowing backwards into the municipal water supply. It consists of two check valves connected in series by an air gap. When one valve closes, a pressure differential is created across the air gap, creating a vaccum seal which prevents contaminated or hazardous water from entering the main water supply line. The backflow preventer also contains a test port where you can insert a pressure gauge to assess if there is any leakage between the two check valves.

Regulations and Codes for Backflow Prevention

Many water systems across the United States are required to abide by certain regulations and codes when it comes to backflow prevention. The purpose of these regulations is to ensure that all water sources are protected from contamination or pollution.

The most common regulation requiring backflow prevention is the Cross-Connection Control Program (CCCP). This program requires that any device or valve installed in a water system is designed to protect the public’s drinking water supply from any potential contamination.

To meet this requirement, many systems will install a backflow preventer device. These devices work by sharing the pressure between two pipes and stopping contaminants from entering the main system. In general, they consist of two check valves connected together with an air gap, allowing excess pressure on one stream to be pushed onto the other.

There are many types of backflow preventers used in different applications, including:

  • Double check valves
  • Reduced pressure zone devices

It’s important to understand what type of device needs to be installed in order to comply with local regulations and codes.


In conclusion, backflow preventers are an important component in any hydronic system as they protect the public water supply from contaminated water re-entering the system. Installing a backflow preventer is easy and can be accomplished without the use of professional plumber. Most importantly, these devices must be tested frequently to ensure they are functioning correctly.

When properly maintained, backflow preventers are reliable devices that provide effective protection of your drinking water and those of your neighbours.

Frequently Asked Questions

Q1: What is a backflow preventer?
A1: A backflow preventer is a device used in plumbing systems to prevent water from flowing in the opposite direction than it should. It is designed to protect potable water supplies from being contaminated by unwanted substances.

Q2: How does a backflow preventer work?
A2: A backflow preventer uses a combination of check valves, valves and air gaps to ensure that water flows in the correct direction. When water pressure changes, the valves will close off and prevent the flow of water in the wrong direction.

Q3: What are the benefits of using a backflow preventer?
A3: Backflow preventers can help protect drinking water from contamination and can help reduce the risk of water-borne diseases. They also help maintain the pressure and volume of water flowing in a plumbing system.

1 thought on “What is a Backflow Preventer and How Does it Work?”

  1. I decided to do a little research on backflow preventers because my cousin has been intending to install one and I don’t know much about them. It’s good that you pointed out that a backflow preventer prevents contaminated or dangerous water from flowing backward into the public water supply. To make sure they are operating properly, it would be helpful to invest in backflow preventer device maintenance services. I’ll absolutely let her know about this so she can keep it in mind and look into services that might be able to assist her with it. I appreciate you sharing!

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