Civil Engineering PE

Answer: C - Air gaps are used to prevent the contamination of a potable water supply. Air gaps are physical separations between supply pipes and receiving vessels, and are required by state drinking water cross-connection control regulations for instances where backsiphonage or backpressure conditions may exist. An example of an air gap in household plumbing is the space between a faucet and a sink. Typically, air gaps are sized vertically to be at least two pipe diameters (minimum 1-inch). There is no available data that suggests the use of air gaps may reduce corrosion within a distribution system or eliminate the need for lift station checkvalves.