All rates and charges for municipal utilities, not fixed by the Public Utilities Commission, shall be fixed, determined and amended by the Council and adopted by resolution. The resolution, containing the effective date thereof, shall be kept on file and open to inspection in the office of the City Clerk and shall be uniformly enforced. For the purpose of fixing the rates and charges, the Council may categorize and classify under the various types of service; provided that, the categorization and classification shall be included in the resolution authorized by this section.