Mo. Rev. Stat. § 91.600
Every city organized and existing under the provisions of Section 16 of Article IX of the Constitution of Missouri of 1875, or Section 19 of Article VI of the Constitution of Missouri of 1945, shall have the right and power to construct, maintain and operate waterworks to supply the city and all persons and parties therein with water and may for such purpose, take, hold, use and dispose of real estate and personal property whether within or outside of the city, or whether within or outside of the state of Missouri, necessary to accomplish such object. It may acquire such property by purchase, donation or an exercise of the power of eminent domain, and may do whatever may be necessary to the exercise of the powers herein granted. Every such city shall have the power to issue its bonds for such purpose to an amount not exceeding the constitutional limitations. Every such city shall have power to make at any time a contract with any such person, corporation, or company, for a period not exceeding twenty years, to furnish water to the city, or to the city and its inhabitants, and to authorize such corporation, person or company, during the existence of such contract, to construct, maintain and operate waterworks in the city. Such contract shall contain a provision reserving to such city the right at its option at any time to acquire and become the sole owner of such portion of the waterworks of such corporation, person or company as may at the time of such purchase be situated in the state of Missouri, on paying a fair and equitable value therefor, to be ascertained, if the parties thereto cannot agree, by the circuit court of the county in which such city is situated, upon the petition of the city, and in such manner as the court may determine; a copy of such petition shall be served upon the corporation, person or company at least fifteen days before the same is presented to the court. The contract above mentioned shall not take effect until an ordinance fully setting forth its terms is submitted to a vote of the voters of the city and approved by two-thirds of the voters voting on the proposition.
§ 91.600, RSMo