What is the minimum height requirement for an atmospheric vacuum breaker above the overflow rim of a vat?

The correct answer is based on established plumbing codes that specify safety and proper installation standards for atmospheric vacuum breakers. An atmospheric vacuum breaker must be installed at least 6 inches above the overflow rim of any fixture, vat, or similar device to prevent backflow and ensure that there is adequate air gap protection. This height is crucial because it helps to avoid any potential siphoning of contaminants back into the potable water supply, should a drop in pressure occur. By adhering to this requirement, a plumber ensures compliance with health and safety standards while effectively safeguarding against contamination risks.