The city council, by motion or resolution, may authorize the city manager or his designated representative to adopt regulations requiring deposits or the prepayment of charges in an amount not exceeding one year's charges either from consumers or occupants of premises receiving benefit of utility services, or both, whichever is appropriate; provided, however, that in case of nonpayment of all or part of a bill said deposits or prepaid charges shall be applied only insofar as necessary to liquidate the cumulative amount of such charges plus penalties and costs of collection. (Ord. No. 952, § 2.)