What is the purpose of an air gap in plumbing?

An air gap serves a crucial role in plumbing by preventing backflow contamination. It is a physical separation between the water supply and potential contamination sources, ensuring that any wastewater or contaminated water cannot siphon back into the drinking water supply. This is essential for maintaining the safety of the drinking water, as backflow can introduce harmful substances into the clean water system. By having an air gap, which is typically implemented as a vertical space between the end of a water supply outlet and the flood level of a fixture, any unwanted backflow can be effectively mitigated.

The other options do not address the primary function of an air gap. While avoiding clogging, allowing drainage, and managing pressure are important aspects of plumbing systems, they do not pertain specifically to the role of an air gap in preventing contamination.