A cross-connection occurs when there is a connection between a potable or drinkable water system and any system containing non-potable water, pollutants, or toxins. An example of where a cross-connection would exist is the piping between consumers’ water systems and an auxiliary water system, a cooling system, or an irrigation system.
Cross-connection often occurs outside the customer service connection, such as within commercial, residential, or industrial plumbing systems. During cross-connection, water supplies become contaminated due to back siphonage or back pressure.

