What is the significance of a proper air gap in backflow prevention?

The significance of a proper air gap in backflow prevention primarily lies in its essential role in protecting potable water supplies from contamination. An air gap is the physical vertical distance between the water supply and the flood level of a fixture or device. This gap serves as a critical barrier that prevents backflow, where contaminated water could otherwise flow back into the drinking water supply due to pressure changes, siphoning, or other influences.

When the air gap is properly maintained, it ensures that there is no direct connection between the non-potable water and the potable water system, thereby safeguarding public health. It is a fundamental safety feature in plumbing systems and is recognized by plumbing codes as a simple yet effective method for preventing backflow contamination.

While other choices mention benefits related to pressure regulation, water flow efficiency, and the possibility of eliminating backflow preventers, these are secondary considerations. The primary function of an air gap is unequivocally to maintain the integrity of the drinking water supply, making option B the correct answer.