How high must a PVB be installed above all downstream piping?

A pressure vacuum breaker (PVB) must be installed at least 12 inches above all downstream piping to ensure proper operation and to prevent any potential backflow contamination. This elevation is crucial because it creates an air gap, which is a necessary safety feature that prevents back siphonage from occurring. If the PVB is positioned too low and there is a drop in system pressure, contaminated water could flow back into the potable water supply.

Installing the PVB at this height also adheres to plumbing codes and standards, which specify that maintaining a minimum distance helps ensure the device can function correctly under varying pressure conditions. By keeping the PVB elevated, it protects the potable water system from potential contaminants that could enter through the downstream piping during negative pressure events.