Mo. Rev. Stat. § 701.050
No person required to provide notice and apply to the city, county or department under section 701.046 may complete the construction, major modification or major repair of an on-site sewage disposal system* without providing notice and an opportunity for inspection by the city, county or department as provided in this section. The person shall notify the city, county or department prior to 9:00 a.m. on the day preceding completion, in the case of contractors registered under sections 701.053 to 701.055, or prior to 9:00 a.m. on the second day preceding completion, in the case of persons not registered under sections 701.053 to 701.055, and the system shall be maintained in a condition which allows for a complete inspection, pursuant to the state standard, until 3:00 p.m. on the day of completion, unless the city, county or department provides confirmation that the system has been inspected and approved prior to that time. The system shall not be closed or completed if the city, county or department determines upon inspection that the system does not meet the state standard, and the city, county or department shall provide, at the time of inspection, a conspicuous marker or other form of notice indicating that the system does not meet the state standard. The city, county or department shall provide written confirmation of the results of the inspection or confirmation that the department did not inspect the system to the property owner within three working days of the day of completion.
§ 701.050, RSMo