How high must a vacuum breaker be installed above the highest lawn sprinkler?

The correct installation height for a vacuum breaker is 12 inches above the highest lawn sprinkler. This requirement is essential to ensure that backflow prevention is effective, helping to protect the potable water supply from contamination. The vacuum breaker works by allowing air into the system when the water pressure drops, preventing any potential siphoning of contaminated water back into the drinking water supply.

By placing the vacuum breaker 12 inches above the highest point of the irrigation system, you create a sufficient air gap, which is critical for the device to function properly. If it were installed lower, there would not be enough separation to prevent backflow during a drop in water pressure, risking contamination. This specific height is a regulatory standard in many plumbing codes to ensure public health and safety in water supply systems.