In this section, “rate consolidation” means the use of the same or similar rates or tariff schedules of rates for customers of the same class for two or more water or sewage disposal systems even if the systems are not physically interconnected. After notice to customers and holding a public hearing and an evidentiary hearing, the Commission may authorize a rate consolidation of two or more water or sewage disposal systems if: the water or sewage disposal systems have common ownership; and the rate consolidation is in the public interest.