Missouri regulations: Wastewater

Missouri regulations governing wastewater discharges are based on the federal Clean Water Act and Water Quality Act and enforced by the Missouri Department of Natural Resources (MDNR). State law regulates discharges of a pollutant from a “point source” (i.e. an identifiable source such as a pipe, ditch, or outfall) to surface water or groundwater. MDNR also regulates land application of biosolids, composting facilities and wastewater irrigation.

“Pollutant” is a broadly-defined term that includes chemicals or chemical compounds that can harm human health, wildlife, fish or aquatic life. It also includes total suspended solids (TSS), biochemical oxygen demand (BOD), phosphorus, oil and grease. The definition of pollutants even includes heat from non-contact cooling water.

Regulated discharges from businesses may include wastewater from restrooms and sinks, wastewater from food processing, spent aqueous cleaning solutions, car wash wastewater, wastewater from industrial processes and boat sewage discharge. Also regulated are housing developments that will require some sort of residential wastewater treatment and the installation of heat pumps.

MDNR discharge permits usually require regular sampling of wastewater at the discharge points and establish the water quality standards for discharges. Pretreatment may be required before some wastes can be discharged into sewage systems. For land application, permits specify the methods by which wastes are handled and disposed.

Most permits are written to be site-specific to reflect the unique nature of the wastewater or the stream it is being discharged into. These permits usually have a five year cycle. General permits are issued to multiple locations where activities are similar enough to be covered by a single set of requirements. All facilities must adhere to the conditions contained in the General Permit until it expires or until the facility obtains a site-specific permit.

Who should apply for a permit?

  1. Is the business constructing sewer lines to connect to an existing community sewer system?
  2. Is the business constructing a wastewater treatment system?
  3. Will the business be discharging wastewater or cooling water into a ditch or body of water?
  4. Will the business dispose of wastewater or sludge off site?
  5. Is the business undertaking a project that involved confined animal feeding?
  6. Is the business undertaking a project that involves on-site liquid waste disposal for more than six households?

A “yes” answer to any of these questions may indicate that the business is required to obtain a permit from the MDNR. Contact the Water Protection Program – Water Pollution Control Branch or your MDNR Regional Office.


For more information on wastewater permit requirements, see MDNR’s Environmental Permits and How to Obtain Them.