What is the minimum distance required for an air-gap separation?

What is the minimum distance required for an air-gap separation?

• A. 1 inch or twice the diameter of the supply pipe, whichever is greater
• B. 1/2 inch
• C. 3 inches
• D. The same as the supply pipe diameter

Answer: (A)

Air-gap separation relies on a physical vertical gap to prevent backflow contamination. By keeping a clear space between the potable water outlet and any potential source of contamination, you create a true break in the water path that air and gravity prevent from being bridged by siphon or backpressure. The minimum distance is defined as the greater of 1 inch or twice the diameter of the supply pipe. This means small-diameter lines still get at least a 1-inch gap, while larger supply pipes require a proportionally larger gap to ensure the potential backflow can’t reach the potable supply. For example, a 1/2-inch pipe needs at least 1 inch, whereas a 3/4-inch pipe requires 1.5 inches, and a 1-inch pipe would require 2 inches. So the best answer reflects that the air-gap must be the larger value between 1 inch and twice the supply-pipe diameter.

Air-gap separation relies on a physical vertical gap to prevent backflow contamination. By keeping a clear space between the potable water outlet and any potential source of contamination, you create a true break in the water path that air and gravity prevent from being bridged by siphon or backpressure.

The minimum distance is defined as the greater of 1 inch or twice the diameter of the supply pipe. This means small-diameter lines still get at least a 1-inch gap, while larger supply pipes require a proportionally larger gap to ensure the potential backflow can’t reach the potable supply. For example, a 1/2-inch pipe needs at least 1 inch, whereas a 3/4-inch pipe requires 1.5 inches, and a 1-inch pipe would require 2 inches.

So the best answer reflects that the air-gap must be the larger value between 1 inch and twice the supply-pipe diameter.