Mo. Rev. Stat. § 341.150
It shall be the duty of the plumbing supervisor to examine or cause to be examined all applications and proposed plans for the installation of plumbing and drainlaying, including all combined storm water and sanitary sewer or sanitary sewers and all connections thereto, and he shall examine and inspect all sewage treatment devices or equipment of whatever character and if found to be in conformity with the provisions of sections 341.090 to 341.220 and regulations adopted pursuant thereto, he shall approve such proposed installation and equipment and shall issue permits for the installation thereof. He shall be required to investigate any report of the installation of defective work or materials not in conformity with the provisions of sections 341.090 to 341.220, and derogatory to established principles of public health and shall require the correction of such defective installation. He shall inspect or cause inspection to be made of all water and sewer connections, and all repairs to water and sewer pipes where an excavation is required, all rough and finished plumbing installations, materials and fixtures, and all drainlaying, sanitary sewers and all connections thereto, and any and all sewage treatment, equipment or facilities, and require their installation in compliance with the provisions of sections 341.090 to 341.220 and the regulations adopted pursuant thereto. He shall report to the prosecuting attorney any and all violations of sections 341.090 to 341.220 or the regulations adopted pursuant thereto. He shall supervise the department of plumbing and sewer inspection and shall keep a proper book record of all transactions and shall make annual report thereof to the county commission and shall collect all fees required to be paid under the provisions of sections 341.090 to 341.220 and shall pay the same promptly into the county treasury.
§ 341.150, RSMo