What is an air gap in plumbing?

An air gap in plumbing refers to an unobstructed air space between a clean water outlet and the fixture rim. This design is crucial for preventing backflow, which can occur if there's a sudden drop in pressure in the water supply line. The air gap acts as a physical barrier that stops contaminants from entering the clean water supply, ensuring the safety and quality of drinking water.

This principle is particularly significant in situations where water might drain back into the supply system, such as in sinks or bathtub spouts. An effective air gap will not only comply with plumbing codes but also protect public health by maintaining the integrity of potable water.

The other options describe different aspects of plumbing or are not related to backflow prevention. A sealed connection between two pipes might be ideal for certain scenarios, but it does not serve the same purpose as an air gap regarding the prevention of contamination. Clutter around plumbing fixtures does not relate to the functionality of water supply systems, and a pressure regulator, while essential for managing water pressure, also does not offer the preventive aspect of backflow that an air gap does.