It shall be unlawful for any person, firm, or corporation at any time to make or maintain or cause to be made or maintained, temporarily or permanently:
A. Any cross connection between plumbing pipes or water fixtures being served by an approved water supply and plumbing pipes or fixtures being served by any other source of water, or
B. To maintain any sanitary fixture or other appurtenance or fixture which, by reason of its construction, may cause or allow backflow of water or other substances into the water supply system of the city and/or the water service of any consumer of the city. (1988 Code)