Backflow Prevention Practice Exam

What’s the minimum vertical distance for an air gap between the outlet of a faucet and the flood-level rim of a sink?

1. 1 inch

2. 2 inches

3. 3 inches

4. 4 inches

The correct answer is: 2 inches

The minimum vertical distance for an air gap between the outlet of a faucet and the flood-level rim of a sink is crucial for effective backflow prevention. An air gap is essentially a physical separation that prevents contaminants from siphoning back into the clean water supply. In this context, a distance of 2 inches is the recognized standard for an air gap in most plumbing codes, such as the Uniform Plumbing Code (UPC) and the International Plumbing Code (IPC). This standard ensures that even if backflow occurs due to pressure changes or siphoning effects, there is a sufficient gap that separates the potable water from potential contaminants or wastewater within the sink. A gap of 2 inches is widely accepted as it balances safety and practicality, providing adequate separation without imposing unnecessary restrictions on plumbing design or function. The choice of a minimum of 2 inches helps to protect the public's health by minimizing the risk of backflow events. Therefore, selecting a vertical distance of 2 inches optimally meets regulatory safety standards.