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 signed by the system owner must be filed with the NPDES Section of the Iowa DNR prior a discharge from an onsite system. A NOI must be submitted when a construction permit for a new discharging onsite system is issued by the local administrative authority, or when a facility (e.g., home, business, etc.) with an existing discharging onsite system is purchased. The NOI form may be obtained from a county sanitarian or downloaded below. By signing the NOI, the system owner agrees to abide by the conditions of the permit. There is no fee associated with permit coverage. Once a signed NOI form is received, the Iowa DNR will issue an authorization for coverage under GP #4 to the system owner.
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, or if a connection is made to a sewer, 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.