Septic Systems Receiving Wastewater Other Than Domestic Sewage

Iowa Administrative Code (IAC) 567- Chapter 69.8(1)d states: “Septic tanks shall not be used for the disposal of chemical wastes or grease in quantities which might be detrimental to the bacterial action in the tank or for the disposal of drainage from roof drains, foundation drains, or area drains”. Iowa DNR interprets this rule to mean disposal of wastewater other than domestic sewage in a septic system is prohibited. Therefore, wastewater from industrial processes, parts washing, vehicle/equipment washing, etc. may not be discharged to a septic system.

EPA has additional regulatory requirements and restrictions on the disposal of industrial and commercial waste into septic systems. A septic system is subject to EPA’s Underground Injection Control program requirements as a Class V injection well if it receives any industrial or commercial wastewater. Class V wells are a concern because they pose a risk to groundwater.  Class V wells receiving motor vehicle wastewater (e.g., fluids from vehicle repair or maintenance activities) may be banned or need to meet new requirements.  Information on Class V wells and motor vehicle waste disposal wells is available through the links on the right.

Industrial or commercial wastewater disposal alternatives include the following. Each of these alternatives entails other regulatory requirements that should be fully understood and considered prior to implementation.

• Connecting to a municipal sanitary sewer system
• Wastewater recycling and reuse
• Storage and transport to a municipal sanitary sewer system
• Storage and transport to a commercial waste management company
• Evaporation

State of Iowa Regulations for Private Septic Systems that Receive Only Domestic Sewage

Septic systems serving 15 people or less are regulated by local boards of health (i.e. counties) while the Iowa DNR has primary responsibility for larger (public) systems. Counties must comply with the minimum state standards. If counties fail to adopt or enforce these standards, Iowa DNR has the authority to enforce them.

Septic systems that receive only domestic sewage at a design rate of less than 1,500 gallons per day (i.e., systems serving 15 people or less) are regulated in accordance with county rules and Iowa DNR regulations contained in IAC 567 - Chapter 69.  Contact your county sanitarian or health department for specific permitting procedures and requirements.

Septic systems that receive only domestic sewage at a design rate greater than 1,500 gallons per day (i.e., a building with over 15 occupants) must obtain a construction/modification permit from the Iowa DNR in accordance with regulations contained in IAC 567 - Chapter 64.  This requires submittal of a Wastewater Construction Permit Application, adequate engineering plans and specifications to allow thorough Iowa DNR review, and a site survey by Iowa DNR field office staff.

EPA Requirements for Large Capacity Septic Systems

Septic systems that receive solely sanitary waste from multiple dwellings or a non-residential establishment and has a capacity to serve 20 or more persons per day is a Large Capacity Septic System (LCSS).  In addition to the requirements listed above, LCSSs must be registered with the EPA as Class V injection wells.