(1) No rate made, deposit or service charge demanded or received by any public utility shall exceed that which is just and reasonable. Such public utility, the rates of which are subject to regulation under the provisions of this article, may demand, collect and receive fair, just and reasonable rates for the services rendered or to be rendered by it to any person. Rates prescribed by the commission shall be such as to yield a fair rate of return to the utility furnishing service, upon the reasonable value of the property of the utility used or useful in furnishing service.

(2) Such utility shall furnish adequate, efficient and reasonable service, and may establish reasonable rules governing the conduct of its business and the conditions under which it shall be required to render service. The commission may, after hearing upon reasonable notice had, upon its own motion or upon complaint, ascertain and fix just and reasonable standards, regulations and practices of service which are to be furnished, imposed, observed and followed by all public utilities. The commission may require the service, rules and regulations of each public utility to be filed with the commission and subjected to its approval or to such changes therein as the commission reasonably may require. Practices required or sanctioned pursuant to the provisions hereof shall supersede other requirements of law.

(3) Such utility may employ in the conduct of its business suitable and reasonable classifications of its service, patrons, rates, deposits and service charges. The classification may, in any proper case, take into account the nature of the use, the quantity and quality used, the time when used, the purpose for which used, and any other reasonable consideration.