What is one purpose of an air gap in plumbing systems?

An air gap plays a vital role in plumbing systems by preventing the contamination of potable water supplies. It is defined as a vertical space between the highest point of a fixture, like a faucet or sink, and the highest level of water in a connected vessel, creating a physical barrier. This design ensures that if there is a backflow situation, where potentially contaminated water attempts to flow back into the clean drinking water system, it cannot do so because the air gap stops the water from reaching the potable supply.

This preventative measure is critical for maintaining safe drinking water, as it effectively eliminates the risk of pollutants or toxins entering the water system, which can occur from cross-connections between potable and non-potable water lines. The presence of an air gap is a fundamental safety feature mandated in plumbing codes to protect public health, ensuring that clean water remains uncontaminated. Other choices, while they may hold some relevance in different contexts, do not pertain directly to the primary purpose of an air gap in plumbing systems.