General Permit #4

Discharge from Private Sewage Disposal (Onsite) Wastewater Treatment and Systems

Any onsite wastewater treatment system (also known as a private sewage disposal system) that discharges treated wastewater to a designated water of the state or a subsurface drainage tile must be monitored to ensure that it meets secondary treatment standards. To achieve these standards, all surface-discharging onsite systems must obtain coverage under NPDES General Permit #4 (GP #4) and must meet all the monitoring requirements of the permit.

NPDES General Permit #4 for Private Sewage Disposal Systems


GP #4 Notice of Intent (NOI)

A Notice of Intent (NOI) form must be filed with the NPDES Section of the Iowa DNR prior to the installation of the discharging onsite system. The NOI form may be obtained from a county sanitarian or downloaded below. Once the form is received, the Iowa DNR will issue a General Permit #4 to the system owner. There is no fee associated with permit coverage.

Submit NOIs to the Iowa DNR at npdes.permit.application@dnr.iowa.gov, or to: NPDES Section, Onsite Coordinator, Iowa Department of Natural Resources, 502 E. 9th Street, Des Moines, IA 50319.


GP #4 Sampling Requirements

The owner of a discharging onsite system is required by GP #4 to sample the discharge from the onsite wastewater system at least twice per year, and to maintain sampling records. These requirements are in addition to any county construction or operating permit requirements for the system. The owner is required to make arrangements for the test samples from the system to be analyzed by a certified laboratory. To find a certified laboratory, please use the State Hygienic Laboratory certified laboratories search. The sample results must be submitted to the Iowa DNR at npdes.mail@dnr.iowa.gov, or to: NPDES Section, Onsite Coordinator, Iowa Department of Natural Resources, 502 E. 9th Street, Des Moines, IA 50319.

If there is no evidence of a discharge from the system within the previous six months, only a physical inspection of the discharge area for any signs of surfacing effluent is required. If no sample is collected, the following Notice of Non-Discharge form (NND) must be completed and submitted.

Submit NDDs to the Iowa DNR at npdes.mail@dnr.iowa.gov, or to: NPDES Section, Onsite Coordinator, Iowa Department of Natural Resources, 502 E. 9th Street, Des Moines, IA 50319, and to the local County Environmental Health program.


GP #4 Notice of Discontinuation (NOD)

If a discharging onsite system is modified to a system that does not discharge to a designated water of the state or a subsurface drainage tile, the owner of the system must submit a Notice of Discontinuation (NOD).

Submit NODs to the Iowa DNR at npdes.mail@dnr.iowa.gov.


GP #4 Questions

Direct questions or comments regarding General Permit #4 to Tim Grotheer at tim.grotheer@dnr.iowa.gov or 515-452-7646.



Renewal of NPDES General Permit #4 for Private Sewage Disposal Systems

On November 15, 2022, the Environmental Protection Commission adopted a final rule to renew GP 4. The renewed permit will become effective on March 1, 2023. For more information on the GP #4 renewal, please see the NPDES Rules page.