What is an air gap?

• A. A link between safe and unsafe water.
• B. A device that aerates water.
• C. A gap in the water supply line.
• D. A connection between hot and cold water.

Answer: (A)

An air gap is a physical separation that prevents backflow of contaminated water into the clean water supply. It creates an unpressurized space between the outlet of the potable water and the highest point of the receptacle or drain, so if pressure changes occur, contaminated water cannot be siphoned back into the safe supply. This simple, unobstructed gap is the most reliable form of backflow protection because it doesn’t depend on valves or devices that could fail. It’s not a device that aerates water, not a gap in the water supply line, and not a connection that mixes hot and cold water.