Mo. Rev. Stat. § 88.650
All cities in this state of the third class and cities with special charter containing three thousand inhabitants and less than thirty thousand inhabitants are authorized and empowered to enact ordinances to pay the cost of laying and extending water main pipes by said cities by levying a special assessment, as herein provided, on the lots and tracts of land fronting or abutting on either side of the street, avenue or alley along the distance so improved in proportion to the front foot, whenever a majority of the resident owners of the property liable to taxation therefor and who shall own a majority of the front feet owned by residents of the city abutting on the street or alley along which the improvement is to be made shall petition the city council or other legislative body for such improvement, or whenever such body in its discretion, shall deem extension of water mains necessary for sanitary or other purposes conducive to the public welfare.
§ 88.650, RSMo