Where OpenSWMM 6 meets ICM, and where they part ways.
This is the newest of the six topics, and it grows through December 2026. It starts with the Control Section Lab: one reference solver, EPA SWMM 5.2.4 and OpenSWMM 6 compiled to WebAssembly, and the documented ICM 1D rules, which predict a steady profile you can test in your own copy of ICM.
Start here
- How the Control Section Lab Works. A reference solver, two SWMM engines and the InfoWorks ICM rules.
- The Road to SWMM6. Where SWMM6 came from and where it is going.
Try a tool
- SWMM and ICM Control Section Lab. EPA SWMM 5.2.4 and OpenSWMM 6 against an exact solution, with ICM’s rules alongside.
- Four-Engine Pipe Comparator. HEC-RAS Pipes, InfoWorks ICM, EPA SWMM5 and the SWMM6 track, compared feature by feature with a shared benchmark.
- Four Engines: The Comparison Plan. The plan behind the four-engine comparison.
Work through an example
- Converting ICM InfoWorks PRN Files to CFS Units for SWMM5 Comparisons. The first step in any ICM comparison: matching units.
Code and automation
- dickinsonre/SWMM-ICM-StVenant. How SWMM5 and ICM solve the St. Venant equations, animated.
- HydroCouple/openswmm.engine. The OpenSWMM 6 engine.
Recently added
- How the Control Section Lab Works. October 2026.
Explore the archive
- SWMM5 and ICM InfoWorks. The topic that comes before this one.
- Inside SWMM6. The engine on the other side of this comparison.
- Engine Comparisons (older topic page). Earlier engine comparisons.
Explore the six topics
- SWMM History: SWMM1 to SWMM6
- Inside SWMM5
- SWMM5 and ICM InfoWorks
- ICM InfoWorks and SWMM6 (this page)
- Inside SWMM6
- Comparing Models with AI
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Use of AI: Claude (Anthropic) drafted this page in November 2026. It picked the entries from my swmm5.org posts, Netlify apps and GitHub repositories and wrote the one-line descriptions. I chose the six topics and the layout.