Mo. Rev. Stat. § 91.070
Any city, town or village, which any city of this state having waterworks may agree to supply with water under the provisions of section 91.060, is hereby authorized and empowered to conduct the water from the city agreeing to supply the same, and for that purpose to lay mains and pipes and to put in, maintain and operate all necessary machinery, apparatus and devices necessary for and in the conducting of the water from the city agreeing to supply the same into its own limits in, upon, over and through any territory of this state, outside as well as within the limits of any such city, town or village, and to connect with the mains of such city agreeing to supply it with water, with the consent of such city supplying the same, and at such place or places and in such manner as such city supplying the water may permit and direct.
§ 91.070, RSMo