Who Regulates Wastewater in Missouri? - PUB1296

The purpose of this publication is to explain the basics of which governmental agencies have jurisdictional responsibility for regulating wastewater in Missouri. Different state and local agencies have responsibility for regulating various wastewater treatment systems, from a simple septic system serving a single family residence to a centralized wastewater collection and treatment system serving an entire community. 

10 CSR 20-2.010(26) defines domestic wastewater as “wastewater (i.e., human sewage) originating primarily from the sanitary conveniences of residences, commercial buildings, factories and institutions, including any water which may have infiltrated the sewers. Domestic wastewater excludes stormwater, animal waste, process waste and other similar waste.”

10 CSR 20-6.015(1)(B)10 defines process waste as “The waste, wastewater, sludges, biosolids and residuals originating from sanitary conveniences, or generated during manufacturing or processing, or results from the production or use of any raw material, intermediate product, finished product, byproduct or waste product and includes discharges from land application fields that occur as a result of the land application process.”

Missouri Department of Health and Senior Services or Local On-site Wastewater Authority

The Department of Health and Senior Services' On-site Wastewater Treatment Program or the local on-site wastewater authority, commonly the county health department, has jurisdiction limited to the following domestic wastewater treatment systems:

1. An individual on-site wastewater treatment (septic) system with subsurface soils dispersal that serves a single family residence.
2. An individual lagoon (earthen basin) that serves no more than a single family residence.
3. Cluster or centralized systems with subsurface soil dispersal under the same common promotional plan within the same operating location when the maximum daily flows of domestic wastewater is less than or equal to 3,000 gallons per day (gpd) including offices, motels/hotels, RV parks, theaters and restaurants.

Missouri Department of Natural Resources

The Missouri Department of Natural Resources’ jurisdiction and responsibilities include:

1. The approval for the method of domestic wastewater treatment in new residential housing developments, such as subdivisions, recreational developments and multiple family housing units, and the expansion of an existing development if it meets specific criteria.
2. All wastewater treatment systems with direct point source discharges and all surface land application systems regardless of maximum daily flows or type of waste treated.
3. All lagoons (earthen basins), other than an individual single family residence lagoon, regardless of maximum daily flows or type of waste treated.
4. Any facility that has a maximum daily flow of domestic wastewater greater than 3,000 gpd.
5.  All wastewater not defined as domestic wastewater, such as stormwater and wastewater generated from nonresidential sources such as wineries, slaughterhouses, dog kennels and industrial manufacturing.

Calculating Maximum Daily Flows vs. Water Use Data to Determine Jurisdiction

Calculating Maximum Daily Flows of Domestic Wastewater

Table 2A–Quantities of Domestic Sewage Flows within 19 CSR 20-3.060 Minimum Construction Standards for On-Site Sewage Disposal contains the criteria to calculate maximum daily design flows when determining jurisdictional responsibility for all new on-site wastewater treatment systems, or when increasing the daily flows for an existing on-site wastewater treatment system.

When a facility proposes two or more cluster systems within the same operating location and each system is designed to treat less than or equal to 3,000 gpd of domestic wastewater, the flows must be calculated together to determine jurisdiction regardless of the number of cluster systems. Individual on-site wastewater treatment systems serving a single family residence are not used to calculate maximum daily flows as described above.

Determining Jurisdiction Utilizing Water Use Data

The determination of jurisdiction for existing domestic wastewater treatment systems must use accurate and verifiable daily water use data. The water use data should be sufficient to reflect an acceptable period of time with respect to the nature of use of the facility. Some examples of an acceptable period of time for the nature of use include: 

• A grade school year – late August through mid-May.
• A typical season for an RV park or campground – April through mid-September.
• A full year for Mobile Home Park or other permanent residence with year-round living. 

If daily water use records are not available, averaging the monthly billing records for the period the facility is in use to calculate flows is an alternative. An example would be if a public grade school is open Monday through Friday with minimum activities on any given Saturday, then the calculations should be based on the days of the week the school is open during the school session minus holidays. To support that documentation, it should be compared to the criteria set forth in Table 2A–Quantities of Domestic Sewage Flows.

It is at the discretion of the Department of Health and Senior Services’ On-site Water Treatment Program or the local on-site wastewater authority whether to accept any water use records when determining jurisdictional responsibility or to request additional documentation as needed.

Flow Chart and Decision-Making

Flow Chart 1

Flow Chart 1, located online at Jurisdiction Flow Chart, describes jurisdiction for residential housing developments, single family residences with or without an in-home business, cluster systems, multiple-family developments. Typical in-home businesses include, but are not limited to, daycares, beauty salons, catering, canning and/or preserving, bakeries and offices.

When the residence with or without an in-home business has an individual on-site wastewater treatment system with a subsurface soil dispersal system, it is the jurisdiction of the Department of Health and Senior Services’ On-site Wastewater Treatment Program, or local on-site wastewater authority as appropriate, as long as any in-home business produces domestic wastewater only. A single family residence with an in-home business served by an individual lagoon may also be the jurisdiction of the Department of Health and Senior Services' On-site Wastewater Treatment Program or local on-site wastewater authority provided the flows from the business are only domestic wastewater and less than 50% of the maximum daily design flow for the single family residence, and it is not located in a separate detached building.

Flow Chart 2

Flow Chart 2, located online at Jurisdiction Flow Chart, describes jurisdiction for waste generated from commercial facilities, which may generate domestic and non-domestic wastewater. As described above, both departments consider wastewater generated at small bakeries and establishments engaged in canning, or the preservation of fruits and vegetables, to be domestic wastewater with respect to jurisdiction. Regardless of jurisdiction, waste produced from many of the facilities listed in Flow Chart 2 is typically high strength waste and should be treated as such in the design, installation and maintenance of the wastewater treatment system.

To help understand the risk high strength waste poses to the environment, consider the difference between domestic wastewater from a single family house and processed wastewater produced from a brewery. Typical effluent from a septic tank serving a single family home has a Biological Oxygen Demand (BOD5) less than or equal to 170 milligrams per liter (mg/l) with the Total Suspended Solids (TSS) being less than or equal to 60 mg/l. Processed wastewater generated from a brewery can have BOD5 between 1,609 to 3,980 mg/l with TSS ranging from 530 to 3,728 mg/l. Untreated or minimally treated processed wastewater with high BOD5 and/or TSS can adversely impact the environment.

There are scenarios that this and other publications may not be able to answer. If you have any questions concerning any project please contact the Department of Natural Resources or the Department of Health and Senior Services' On-site Wastewater Treatment Program at 800-628-9891 or 573-751-6095.