A district may charge reasonable connection charges to defray in whole or in part the cost of providing sewage disposal service and may levy and collect annual or semiannual charges to cover the cost of maintenance and operation of the sewage disposal system. Any charges authorized by this section shall be made only within the area to be served. If the sewage disposal service is provided to only a portion of the district, the area so served shall bear all costs of the maintenance, operation, and administration of such service.