What is a cross-connection?

A cross-connection is a point in a plumbing system where the potable water supply is connected to a non-potable source. Briefly, a cross-connection exists whenever the drinking water system is or could be connected to any non-potable source (plumbing fixture, equipment used in any plumbing or irrigation system). Pollutants or contaminants can enter the safe drinking water system through uncontrolled cross connections when backflow occurs.