What term describes reverse flow in a water supply caused by a vacuum?

What term describes reverse flow in a water supply caused by a vacuum?

• A. Backpressure
• B. Back Siphonage
• C. Air lock
• D. Hydraulic shock

Answer: (B)

Back siphonage describes reverse flow caused by a vacuum or negative pressure in the water supply. When the pressure in the public system drops below the pressure in the household or building piping, water can be siphoned backward through cross-connections into the supply line. This is driven by the suction created by the lower pressure downstream, effectively pulling water back toward the source. This is different from backpressure, where reverse flow happens because downstream pressure is higher than the supply (often from pumping or elevation). It also isn’t an air lock, which is simply an air pocket that temporarily blocks flow, nor is it hydraulic shock, which is a pressure surge caused by sudden changes in flow. Back siphonage is the specific risk when negative pressure pulls water back into the supply through a cross-connection.

Back siphonage describes reverse flow caused by a vacuum or negative pressure in the water supply. When the pressure in the public system drops below the pressure in the household or building piping, water can be siphoned backward through cross-connections into the supply line. This is driven by the suction created by the lower pressure downstream, effectively pulling water back toward the source.

This is different from backpressure, where reverse flow happens because downstream pressure is higher than the supply (often from pumping or elevation). It also isn’t an air lock, which is simply an air pocket that temporarily blocks flow, nor is it hydraulic shock, which is a pressure surge caused by sudden changes in flow. Back siphonage is the specific risk when negative pressure pulls water back into the supply through a cross-connection.