Which of the following is NOT recommended to protect against back pressure backflow?

The Atmospheric Vacuum Breaker is designed primarily to protect against back siphonage, not back pressure backflow. Back pressure occurs when the pressure in the non-potable system exceeds that of the supply line, potentially causing contamination. The recommended devices for preventing back pressure backflow include the Double Check Valve Assembly, which provides a means to prevent backflow when there is no pressure differential, and the Reduced Pressure Zone Device, which is specifically engineered to prevent both back pressure and back siphonage by maintaining a reduced pressure within the potable water supply.

In contrast, while Atmospheric Vacuum Breakers effectively prevent back siphonage by breaking the vacuum that could draw contaminants into the potable water supply, they are not equipped to handle situations where back pressure is a concern. This makes them unsuitable for protection against back pressure backflow, thus solidifying their position as the correct choice for the question.