Cross-connection of the public water supply system and any other water supply system or source, including but not limited to the following, are prohibited:
A. Between a public water supply system and a secondary water supply.
B. By submerged inlet.
C. Between a lawn sprinkling system and the public water supply system.
D. Between a public water supply and piping which may contain sanitary waste or a chemical contaminant.
E. Between a public water supply system and piping immersed in a tank or vessel which may contain a contaminant. (1988 Code §20.107)