What is the primary characteristic of the air gap used as a backflow prevention method?

The primary characteristic of the air gap used as a backflow prevention method is its ability to separate drinking water from contaminants. An air gap is a physical distance between the water outlet and the highest possible water level of a receptacle to ensure that backflow cannot occur. By maintaining this separation, the air gap effectively prevents potentially contaminated water from flowing back into the potable water supply, thus protecting public health and maintaining the quality of drinking water.

This method is crucial in settings where there's a risk of contamination, as it provides a simple yet effective barrier against backflow that could introduce harmful substances into the water supply. The air gap is a recognized standard in plumbing codes due to its reliability in preventing cross-contamination.