It is expressly provided that there shall be no private sewerage disposal systems, cesspools, septic tanks, drain fields, vaults or other means of collection of sewerage in the city. All sewerage from any building or structure in the city shall be collected by the city sewer system unless a variance is granted by the mayor and city council for installation of a septic tank and drain field to be constructed outside of the city limits to collect sewerage from a private residence or building. (Ord. 323 § 2, 1985)