Which term refers to the physical connection between two separate piping systems that could allow flow between them?

The term that refers to the physical connection between two separate piping systems that could allow flow between them is known as a cross connection. This situation can pose a risk of contamination if one system is pressurized and can draw water from another system, potentially mixing potable and non-potable water supplies.

Cross connections are particularly critical to monitor and prevent because they can lead to backflow, which compromises the safety of drinking water. The implications of cross connections are heavily regulated in plumbing codes to ensure the integrity of water systems and protect public health.

The other terms listed pertain to different aspects of plumbing systems. A drain is simply a pipe that removes waste water or excess liquid, a dead end refers to a portion of piping where water cannot flow any further, and a double offset is a configuration used to change the direction of pipes without creating sharp bends. These definitions highlight that they do not address the specific situation of interconnection between two systems like a cross connection does.