Are air gaps subject to backflow?

Air gaps are designed to prevent backflow in plumbing systems, particularly in scenarios where non-potable water could contaminate potable water supplies. An air gap provides a physical separation between the outlet of a water supply pipe and the highest point of the fixture or appliance that draws the water. This design ensures that there is no direct connection that could allow water to flow backward due to potential negative pressures in the system.

Because of this physical separation, air gaps effectively eliminate the risk of backflow, regardless of the water conditions or pressure scenarios. Thus, they are not subject to backflow. This distinguishes air gaps from other backflow prevention devices, which may allow for backflow under certain conditions, such as backpressure or backsiphonage.

Understanding the fundamental principle of air gaps in preventing contamination from backflow helps underscore their importance in ensuring safe drinking water and compliant plumbing infrastructure.