What type of protection does an air gap provide?

An air gap is a crucial component in plumbing and water safety, specifically designed to prevent contamination of potable water supplies. Its primary function is to provide protection from back siphonage and back pressure.

When there is a change in pressure within a plumbing system, such as during a drop in water pressure or when water flows in a reverse direction, contaminants can be drawn back into the clean water supply. This phenomenon is known as back siphonage. An air gap creates a physical separation between the water supply and any potential contaminants in a sink or other receptacle. By ensuring that there is an unobstructed vertical space between the end of the water outlet and the contaminated water source, it effectively prevents any backflow.

In addition to back siphonage, the air gap also helps guard against back pressure, which can occur if the pressure in the supply line exceeds the pressure in the downstream system. The air gap ensures that even in scenarios of back pressure, there is no opportunity for water to flow back into the clean supply.

This protective measure is essential in maintaining the integrity of drinking water supplies and adhering to health and safety regulations, which is why it is a common practice in plumbing design. The air gap can exist in various applications, such as