For a pump with a sealed water system, which two measures protect potable water from backflow?

• A. Break tank
• B. Air gap
• C. Break tank & air gap
• D. RPZ device

Answer: (C)

Backflow protection relies on creating physical barriers so contaminated water cannot flow back into the potable supply. In a pump with a sealed water system, using two independent measures provides two layers of defense against both backpressure and back-siphonage.

A break tank serves as a separate reservoir on the pump discharge side. It creates hydraulic separation between the potable supply and the pumped water, so even if pressure conditions change or the pump behaves unexpectedly, the water drawn into the pump isn’t drawn directly back into the main potable system. The tank’s connection to atmosphere and its separation from the public supply reduce the chance that contaminated water can re-enter the supply.

An air gap adds a simple, physical separation at the point where water leaves the system. By maintaining a vertical distance with no direct contact between the water outlet and any potential contaminant pathway, it ensures that even if pressure in the downstream piping fluctuates, backflow cannot occur into the potable line.

Together, break tank and air gap provide two barriers: the break tank breaks the water column hydraulically, and the air gap provides a physical separation at the discharge point. This dual approach offers robust protection for potable water in a sealed pump system.