Part IV, individual wastewater disposal systems, of the code of waste disposal regulations, adopted by the state division of health and state committee on water pollution in May 1965, as revised by action of the board in June 1967, and issued and published as a code in book form, three (3) copies of which have been filed for use and examination by the public in the office of the city recorder, and which established rules and regulations relating to the disposal of domestic wastewater discharge from single homes, multiple dwellings containing not more than four (4) individual units, and commercial installations serving not more than fifty (50) persons per day, is hereby adopted by the city as the ordinance relating to individual wastewater disposal systems within the city, except as such code may be altered or modified by the provisions of this section. (1989 Code § 12-510)