Cross Connection: Any unprotected actual or potential connection or structural arrangement between a public or a consumer's potable water system and any other source or system through which it is possible to introduce in to any part of the potable system any used water, industrial fluid, gas, or substance other than the intended potable water with which the system is supplied.
Backflow: The undesirable reversal of water or mixture of water and other liquids, gases or other substances into the distribution pipes of the potable supply of water.
Potable Water Supply: Any system of water supply intended or used for human consumption or other domestic use.
Contamination: The entry into or presence in a public water supply system of any substance which may be deleterious to health and or quality of the water.