OWTS Construction Permit Application Process

A construction permit is required before installing or repairing most onsite wastewater treatment systems (OWTS). First, you must determine what agency has permitting authority for the wastewater treatment system you plan to install or repair. OWTS fall under the authority of a county or city agency if a local onsite sewage ordinance has been adopted. Otherwise, OWTS are under the authority of the Missouri Department of Health and Senior Services (DHSS). Note: For any lot less than three (3) acres in size, a construction permit is required; some single family residential lots that are three (3) acres or larger in size, could be exempt from permitting. However, this exemption does not apply in some jurisdictions. Check with the local authority (see jurisdiction below). The DHSS permit application process is described below.

OWTS regulations cover:
1. Single-family residential systems including lagoons;
2. Onsite or cluster systems that treat domestic wastewater flows of 3,000 gallons per day or less and disperse the wastewater through soil treatment/absorption systems.
Other wastewater treatment systems are regulated by the Missouri Department of Natural Resources (see box).

After confirming that your system falls under onsite system regulations, it is important to know exactly who has permitting authority for your planned system so you can avoid delays and know whether to use the forms available on this website. The application process that you need to follow will depend on the onsite authority in your area. Jurisdictions with a local ordinance will have different processes and forms than what are discussed here. Before beginning a new installation or the repair of an existing system, you or your installer should check with your Local Public Health Agency or other OWTS permitting authority about the permit requirements in your area. To link to the contact information for most permitting authorities in Missouri, select a jurisdiction below based on your system location. Contact the permitting authority to request technical assistance or an application packet.

Click on the county (in the map below) for contact information.

The Missouri Department of Natural Resources (DNR) regulates other wastewater treatment systems in Missouri including:

  1. Lagoons serving anything other than single-family residences;
  2. Systems that treat and discharge into surface waters;
  3. Systems that treat wastewater flows greater than 3,000 gallons per day and disperse wastewater through soil treatment/absorption systems;
  4. Systems that treat industrial (non-domestic) wastewater flows. Contact DNR if there is any question about the type of waste generated at a facility.

In addition, DNR must approve subdivisions, mobile home parks and campgrounds if the use of OWTS is planned. Developers as well as property owners in unapproved developments should contact DNR regarding their residential housing unit requirements. For more information see Who Regulates Wastewater in Missouri or contact DNR.

DHSS Permit Process

If the proposed system falls under DHSS regulation, you must apply to the County Public Health Agency or to DHSS for a construction permit. Select your local jurisdiction from the drop down list above to find which agency to contact and to download DHSS applications, if applicable.

A complete permit application must include everything needed to determine compliance with the Missouri Onsite Sewage Laws and Minimum Construction Standards. Use the application Instructions and Check Off List to insure you are submitting all required information. Generally a site/soil evaluation report must accompany the completed application form. The application should clearly show the system location on a site layout diagram. In addition, an engineer's design must be submitted for certain types of systems, and a variance application may be required if the system size or setback distance requirements cannot be met. Occasionally the permitting authority may require other information, for example, information about a water supply well or about the subdivision where the site is located.

Site/Soil Evaluations

The first step in an OWTS design is to have the site evaluated. A soil morphology evaluation report or percolation test report must be included with the application (see Sample Soil Morphology Evaluation
Form). Only individuals registered by DHSS may perform site/soil evaluations. Direct your browser to the lists of Registered OSE for Registered Onsite Soil Evaluators who work in your county or nearby counties. A soil morphology evaluation is a detailed description of the soil's physical properties and the site's suitability for a conventional OWTS. Soil morphology is not influenced by current weather patterns. Although, the results of a percolation test are more limited and can be affected by recent or seasonal weather patterns, the 'perc test' is still accepted in a few areas. Check with the permitting authority regarding acceptance and a list of registered percolation testers.

The results of the site evaluation will be a main factor in the system selection. The permitting authority will not design your system, but can offer technical assistance with the location and type of system. If the site is classified as 'suitable,' or in some instances 'provisionally suitable' for a conventional gravity system, a Registered OWTS installer should be able to design the onsite system and assist you in completing the application.

If the site/soil evaluation indicates the site is unsuitable for a conventional septic tank and gravity soil absorption system, an advanced OWTS or alternative OWTS may be needed. A Missouri Professional Engineer must design alternative systems and installers of advanced or alternative systems must be registered as advanced OWTS installers.

Pre-construction Site Inspection

Once the completed application has been reviewed and compliance with the rule has been verified, the permitting authority will visit the site to determine if the system that was proposed in the application will "fit" the site. If the proposed system does not fit on the site, then changes will need to be made to the application and proposed system design. If everything checks-out during the pre-construction site inspection, then a construction permit will be issued. The permit is valid for one year and in some cases might be extended provided site conditions are the same and a request is made prior to its expiration.

Construction and Final Inspections

When construction begins, you or your installer should contact the permitting authority. Often, the installation of an OWTS doesn't take very long, once construction has begun, so it is good to keep the permitting authority informed of the project status. It is a requirement that 24 to 30 hours notice, be provided prior to the completion of the system. When possible, a final inspection will be made prior to the system being completed. All parts of the system must be installed as indicated in the application and permit, including fences around lagoons, distribution devices, pumps operational, etc. However, the system must be accessible for inspection for up to 30 hours after the required notification unless you are advised a final inspection will not be conducted. When the permitting authority cannot schedule an inspection, the registered installer will be required to certify that the system was installed according to the approved application/permit. Final system approval will not be given until the installer's certification is received.

Operation and Maintenance

After the system is completed, the owner is responsible for insuring the system is operated and maintained properly. It is important to get a diagram from the installer or designer showing the location of the system. Sewage tanks need to be pumped out and maintenance needs to be performed on a regular schedule. Installers or maintenance service providers may offer service contracts for the system. Maintenance contracts are recommended, especially for advanced OWTS.