What characterizes a cross-connection in plumbing?

A cross-connection in plumbing is fundamentally characterized by the physical connection between potable (safe for drinking and cooking) and non-potable (unsafe for human consumption) water supplies. This connection poses a risk of contamination, as it can allow harmful substances from non-potable water to backflow and mix with the clean water supply, leading to serious health hazards.

Preventive measures, such as the installation of backflow preventers, are critical in plumbing systems to ensure that the integrity of potable water is maintained and that there is no risk of contamination from potentially unsafe sources.

In contrast, a direct connection between two drain pipes does not involve the same risk of contaminating drinking water and therefore does not represent a cross-connection. Similarly, connections allowing steam to escape or devices regulating water flow do not directly pertain to the issue of cross-connections, as they do not involve the mixing of potable and non-potable water.