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Iowa Wastewater Facilities Design Standards (IWFDS)
The IWFDS were adopted in the late 1970's and early 1980's. The Iowa DNR initiated a review of selected Chapters (11, 12, 13, 14, and 18C) in 2018, and revisions were proposed. As part of the required rule review for Executive Order 10 (EO10), all of the chapters in the IWFDS have been reviewed and revised. See the Water Quality Bureau Rulemaking page for more information on EO10 and the rule revisions associated with EO10.
2025 IWFDS Revision
The updated IWFDS will be effective on June 18, 2025.
November 2024 Proposed Changes:
Old IWFDS
- Complete Set of Old Chapters, 12 MG
- Old Chapter 11: Project Submittals
- Old Chapter 12: Iowa Standards for Sewer Systems
- Old Chapter 13: Wastewater Pumping Stations and Force Mains
- Old Chapter 14: Wastewater Treatment Works
- Old Chapter 15: Screening and Grit Removal
- Old Chapter 16: Settling
- Old Chapter 17: Sludge Handling and Disposal
- Old Chapter 18a: Fixed Film Media Treatment
- Old Chapter 18b: Activated Sludge Biological Treatment
- Old Chapter 18c: Wastewater Treatment Ponds (Lagoons)
- Old Chapter 19: Supplemental Treatment Processes
- Old Chapter 20: Disinfection
- Old Chapter 21: Land Application of Wastewater
Ten States Standards
The "Recommended Standards for Wastewater Facilities" by the Great Lakes - Upper Mississippi River Board of State and Provincial Public Health and Environmental Managers, commonly referred to as the Ten States Standards, is referenced in state rules and used by the Iowa DNR to supplement Iowa's Wastewater Facilities Design Standards. This wastewater facilities design document is an update prepared jointly by a board including Iowa, nine other Midwestern states, and the Province of Ontario. The 2014 Edition is available on the Ten States Standards website.
Back to topAlternative Wastewater Treatment Design Guidance Manuals
The DNR has developed design guidance manuals in an effort to provide uniform design guidelines and broaden the number of treatment options considered for managing wastewater within Iowa's communities with populations ranging from 25 to 250. Understanding the alternative design guidance is important for consulting engineers and planners involved in the planning, funding, and design, and construction of wastewater treatment improvement projects since they are not addressed in the current IWFDS. The guidance manuals will enable professionals to evaluate these alternatives and work through the state approval process with confidence.
- Recirculating Media Filter Technology Assessment and Design Guidance Manual
- Sand Mound Technology Assessment and Design Guidance Manual
- Drip Dispersal Systems Technology Assessment and Design Guidance Manual
- Constructed Wetlands Technology Assessment and Design Guidance Manual
- Alternative Collection Systems Technology Assessment and Design Guidance Manual
Alternative Wastewater Treatment Design Guidance Documents - Technology Assessments
Due to revisions to Iowa’s Water Quality Standards, many communities have been faced with more stringent NPDES permit limits for bacteria and ammonia. Communities may experience significant costs associated with upgrading existing or building new wastewater infrastructure to meet effluent limits. These conditions created a need to broaden the treatment options considered for managing wastewater in Iowa communities.
The DNR has evaluated several new technologies for wastewater treatment that are not addressed by detailed design criteria in the IWFDS. After research and data analysis, DNR staff developed the following technical design guidance for alternative wastewater treatment technologies. These treatment technologies were evaluated for technical capability when treating primarily domestic wastewater from small municipal systems without industrial or significant commercial loads. These assessments, in addition to the applicable IWFDS, are intended to provide guidance to designers for project submittals to DNR for review and approval based on current empirical information relative to the capabilities of the treatment technology in various applications. The assessments are not design standards, but when used in conjunction with the IWFDS, should serve as the DNR's expectations for permit approval.
- Assessment No. 09-01 LemTec Biological Treatment
- Assessment No. 09-02 AdvanTex Treatment
- Assessment No. 11-01 SAGR Treatment (Updated December 2016)
- SAGR Example Calculations
- Iowa DNR Design Guidance and Criteria for Sequencing Batch Reactors (SBRs)
Additional Design Guidance Documents
- Geotechnical Reviews Presentation (presented by Iowa Geological and Water Survey 2/21/12)