Mo. Rev. Stat. § 249.1000

A publicly owned treatment works that has ownership of interceptor and local sewers shall be responsible for the entire public sewer system, except that the operation and maintenance of any part of an individual user's pressure sewer system, including grinder or low pressure pumps and service lateral to the public or private pressure sewer system used for the purpose of collecting or conducting wastewater originating at a residence or individual commercial entity, shall be the responsibility of the owner of such residence or individual commercial entity unless the publicly owned treatment works has assumed such responsibility.