What is a "cross connection" in plumbing terms?

A "cross connection" refers specifically to an unprotected connection between potable (drinking) water and non-potable (non-drinkable) water sources. This type of connection poses a serious risk of contamination, as backflow can occur if there is a change in pressure in the system, leading to the potential of harmful substances entering the clean water supply. Recognizing and preventing cross connections is crucial in plumbing to ensure the safety of drinking water. The importance of maintaining separation between these two types of water is a core principle in plumbing regulations and practices to protect public health.

The other choices do not accurately describe what a cross connection is. A secured link between two water sources or a connection to the municipal water supply does not imply any contamination risk unless there is an unprotected connection involved. Similarly, a valve that controls water flow does not pertain directly to the concept of cross connections, as it addresses flow management rather than the safety and integrity of drinking water systems.