Section 53.003 - Just and Reasonable Rates(a) The commission shall ensure that each rate a public utility or two or more public utilities jointly make, demand, or receive is just and reasonable.(b) A rate may not be unreasonably preferential, prejudicial, or discriminatory but must be sufficient, equitable, and consistent in application to each class of consumer.(c) A public utility may not: (1) grant an unreasonable preference or advantage concerning rates to a person in a classification;(2) subject a person in a classification to an unreasonable prejudice or disadvantage concerning rates; or(3) establish or maintain an unreasonable difference concerning rates between localities or between classes of service.(d) In establishing a public utility's rates, the commission may treat as a single class two or more municipalities that a public utility serves if the commission considers that treatment to be appropriate. Acts 1997, 75th Leg., ch. 166, Sec. 1, eff. Sept. 1, 1997.