Storm, surface, ground waters, or any other unpolluted drainage shall be discharged only into such sewers as are specifically designated as storm sewers or to a natural outlet approved by the director of public works. Industrial cooling water or unpolluted process waters may be discharged, upon approval of the director of public works, to a storm sewer or natural outlet. (Ord. 781 §§ 2, 10, 1975; Ord. 147 § 9.02, 1963)