Arizona Plumbing Practice Exam

What is the required minimum air gap for a lavatory faucet with an effective opening of 1/2 inches positioned 3 inches from a wall?

1. 1 inch

2. 2 inches

3. 3 inches

4. 4 inches

The correct answer is: 1 inch

The required minimum air gap for a lavatory faucet is determined by the effective opening size and the proximity to potential contaminants, such as the wall or sink structure. For an effective opening of 1/2 inch, the recommended air gap is typically twice the diameter of the opening, which means the air gap should be at least 1 inch to effectively prevent any backflow issues. This distance helps ensure that any water or contaminants that may rise through a drain do not reach the faucet's supply line, thus maintaining safe drinking water standards and protecting against cross-contamination. In situations where the faucet is positioned closer to surfaces like walls, ensuring this 1-inch air gap is critical. While the other options present larger air gaps, they exceed the minimum requirement and are not necessary for a faucet with a 1/2 inch effective opening. Proper adherence to the 1-inch standard maintains safety without being unnecessarily excessive.