What is the function of an air gap in backflow prevention?

The function of an air gap in backflow prevention is to provide a physical separation between the potable water supply and non-potable sources. This separation is critical in ensuring that water intended for drinking and human consumption does not come into contact with contaminated water sources that could introduce harmful substances or pathogens.

An air gap is created by having a vertical space between the outlet of a potable water system and the highest possible level of liquid that could occur in a fixture or non-potable source. This physical barrier prevents backflow, which is the unwanted reversal of flow in a plumbing system, and eliminates any chance of contamination by ensuring that there is no direct connection between the two water sources.

When plumbing systems are designed, this method is recognized as one of the most reliable backflow prevention techniques, as it does not depend on mechanical parts that can fail. By maintaining this physical distance, the integrity of the drinking water supply can be safeguarded against pollutants and contaminants.