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Double Check Valve Assembly: A Key Player in Backflow Prevention

In the world of plumbing, backflow prevention is a critical concern. One device that plays a significant role in this area is the double check valve assembly. But what exactly is a double check valve assembly, and how does it help prevent backflow? This blog post aims to demystify this essential device and shed light on its role in maintaining a safe and clean water supply.

A double check valve assembly, often abbreviated as DCVA, is a type of backflow prevention device. It consists of two check valves assembled in series, usually with a ball valve or gate valve installed at each end for isolation and testing purposes. The primary function of a DCVA is to prevent backflow, specifically backpressure backflow, in moderate hazard situations.

Backflow occurs when water flows in the opposite direction to its usual flow, potentially contaminating the potable water supply. This can happen due to changes in pressure within the plumbing system, such as backpressure or backsiphonage. A DCVA helps prevent this by allowing water to flow in one direction and blocking it from flowing backward.

The double check valve assembly is a popular choice for backflow prevention due to its reliability and low maintenance requirements. The two check valves provide a level of redundancy; if one valve fails, the other can still prevent backflow. This makes DCVAs a preferred option for many residential, commercial, and industrial applications.

However, while DCVAs are effective in preventing backpressure backflow, they are not suitable for high hazard situations where the water supply could be contaminated with toxins that could cause severe health effects. In such cases, a more robust backflow prevention device, such as a reduced pressure zone device, may be required.

Regular inspection and maintenance of a DCVA are crucial to ensure its effectiveness. Over time, debris or wear and tear can cause the check valves to stick or fail. It's recommended to have a certified professional inspect and test your DCVA annually to ensure it's functioning correctly.


The double check valve assembly is a vital tool in the fight against backflow. By understanding what a DCVA is and how it works, homeowners and businesses can make informed decisions about their backflow prevention strategies. Regular inspection and maintenance of these devices, along with an understanding of when they are appropriate to use, can go a long way in protecting our water supplies from contamination.

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