What is the minimum air gap required at an indirect drain?

The minimum air gap required at an indirect drain is 1 inch. This distance is essential to prevent backflow and contamination of potable water supplies by ensuring that any waste water is effectively separated from the water supply. An air gap is a physical separation between the water outlet and the flood level rim of the fixture, which allows for the prevention of siphoning and potential cross-connections that could introduce harmful substances back into the drinking water system.

While larger air gaps may provide additional safety in certain situations, the standard minimum requirement of 1 inch is widely accepted across various health codes and regulations. This ensures a sufficient barrier to protect against contaminants entering the water supply.