What are domestic water crossover lines?

Domestic water crossover lines refer to pipes that connect different plumbing systems, allowing for the mixing or transfer of water between them. This can occur between potable (drinking) water systems and non-potable systems, such as irrigation or industrial water systems. The presence of crossover lines can introduce risks, especially concerning the potential for contamination of safe drinking water if not properly managed. Understanding the purpose of these lines is crucial in the context of assessing and managing Legionella risk, as they can inadvertently facilitate the spread of pathogens if backflow or cross-connection occurs.

The other explanations would not accurately define crossover lines; for instance, pipes used solely for irrigation would not serve any crossover purpose, nor would pipes that deal exclusively with wastewater drainage or those meant only for outdoor fixtures, as these functions do not involve the interconnection of systems that could impact water quality in domestic settings.