Mont. Code Ann. § 69-7-201

Each municipal utility shall adopt, with the concurrence of the municipal governing body, rules for the operation of the utility. The rules shall contain, at a minimum, those requirements of good practice which can be normally expected for the operation of a utility. They shall define or provide for use of meter or flat-rate user charges, the classification of users, applications for service, and uses of the service. The rules shall outline the utility's procedure for discontinuance of service and reestablishment of service as well as the extension of service to users within the municipal boundaries and outside the municipal boundaries. The rule shall provide that rate increases for comparable classifications and zones outside the municipal boundaries may not exceed those set within the municipal limits under the provisions of this chapter.