Which assembly is effective against backflow from both back pressure and back siphonage?

The double check valve assembly is specifically designed to protect against backflow from both back pressure and back siphonage. It consists of two independently operating check valves placed in series, which provides a higher level of protection than a single check valve. This design ensures that if one check valve fails or is compromised, the second check valve remains functional, helping to prevent contaminated water from flowing back into the potable water supply.

In many plumbing applications, particularly those involving potential cross-connections where a risk of contamination exists, the double check valve assembly meets code requirements and is appropriate for a variety of situations. It effectively reduces the risk of backflow incidents by ensuring both aspects—back pressure and back siphonage—are adequately addressed.

Other options, while providing some level of backflow prevention, do not offer the same comprehensive protection. For example, a single check valve is only effective against back pressure and is insufficient alone for preventing back siphonage. The atmospheric vacuum breaker, primarily designed to prevent back siphonage, cannot handle back pressure situations effectively. The pressure vacuum breaker, while also designed to protect against back siphonage, is not effective against back pressure unless it is installed under specific conditions. Thus, the double check valve assembly stands out as