What does "cross-connection" refer to in water supply systems?

The term "cross-connection" specifically refers to an unprotected connection between potable (drinking) water and a non-potable source. This situation creates a potential pathway for contaminants to enter the safe drinking water supply. Cross-connections pose significant risks to public health and water safety because if the non-potable source becomes pressurized, it can lead to the backflow of contaminants into the potable water supply.

Understanding cross-connections is crucial for ensuring the integrity of water supply systems. To mitigate these risks, various physical devices, like backflow preventers, are used to maintain separation between potable and non-potable systems and prevent contamination.

The other options do not accurately describe what constitutes a cross-connection. A connection between two potable sources does not pose a contamination risk and thus does not fit the definition. A type of water filtration system is unrelated to the concept of cross-connections; filtration is a method for treating water, while cross-connections deal with the risk of contamination. Lastly, legal regulations regarding water usage, while important in managing water systems, do not define what a cross-connection is.