How is an air gap separation measured?

An air gap separation is a critical component of backflow prevention, and it is defined as the vertical distance between the outlet of a water supply system and the flood level rim of the receptacle receiving the water, such as a sink or bathtub. This measurement ensures that there is sufficient space to prevent backflow contamination by allowing air to enter the water system, thus preventing the siphoning of contaminated water back into the clean supply.

The measurement is specifically taken from the outlet (where water is discharged) to the flood level rim, which is the level at which the receptacle would overflow. If the outlet were to become submerged or if a siphon were to occur, water would not be able to flow back into the system due to the air gap. This principle protects drinking water supplies from contaminants, making it a vital aspect of plumbing safety and compliance.

Proper measurement and maintenance of air gaps are essential for ensuring they are effective in preventing backflow incidents, which can have serious health implications.