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Backflow Prevention Device

Backflow Prevention Device

A backflow prevention device is a mechanical device that is intended to prevent the reverse flow of water from a property or premises back into the public water supply. It acts as a barrier, ensuring that the drinking water supply remains separate from any potential sources of contamination within the property.

There are several types of backflow prevention devices available, and the selection of a specific device depends on the level of protection required and the specific application. Here are some common types of backflow prevention devices:

  1. Atmospheric Vacuum Breaker (AVB): This device is typically used in low-hazard applications and features a check valve that opens to allow water to flow into the property but closes to prevent backflow. It includes an air inlet that opens when there is a drop in pressure, creating a break in the water flow and preventing backflow.
  2. Pressure Vacuum Breaker (PVB): PVB devices are commonly used in residential and commercial applications. They feature a check valve and an air inlet valve, similar to an AVB. However, a PVB also includes a built-in, spring-loaded air inlet valve that stays closed during normal operation but opens under a drop in pressure, creating a barrier against backflow.
  3. Double Check Valve Assembly (DCVA): DCVAs are commonly used in medium-hazard applications. They consist of two independently operating check valves, providing an additional layer of protection. These devices also include test cocks for regular testing and verification of their functionality.
  4. Reduced Pressure Zone (RPZ) Assembly: RPZ assemblies are used in high-hazard applications. They consist of two check valves and a relief valve between them, creating a zone of reduced pressure. The relief valve opens when there is a drop in pressure, preventing backflow and ensuring that any potential contaminants are discharged to a drain.

These are just a few examples of backflow prevention devices, and there may be other types available depending on the specific requirements and regulations in different regions. It's important to consult local plumbing codes and regulations to determine the appropriate type of backflow prevention device for a particular application. Additionally, regular maintenance, testing, and certification of backflow prevention devices are essential to ensure their proper functioning and effectiveness.


In preparing this definition, we have drawn from various sources including Legislation, Codes, Standards and industry information, research and knowledge.  Like the english language, these definitions may subtly change from time to time. As such these definitions are provided solely on the basis that users will be responsible for making their own assessment of the definition and and are advised to verify all relevant representations, statements and information.