Enacts new GS 62-133.12A. Authorizes the Utilities Commission to adopt, implement, modify, or eliminate a rate adjustment mechanism for one or more of a water or wastewater utility's rate schedules to track and true-up variations in average per customer usage from levels approved in a general rate proceeding. Adoption requires a finding by the Commission that the mechanism is appropriate for that purpose, and that the mechanism is in the public interest.