Reference Hub for EPA SWMM5, SWMM6, and ICM InfoWorks Modeling

1,729+ articles, 150+ Ruby scripts, and 99+ free interactive tools from Robert Dickinson, SWMM engine contributor since the 1970s and SWMM5+ TAC chair.

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Ephemeralization, checking and hand-thinking for SWMM5, SWMM6 and models in general 01 Nov 2026
The Stairs and the Lift Ephemeralization, checking and hand-thinking for SWMM5, SWMM6 and models in general SWMM Enablement · 2026-10-31 · companion to the SWMM App Complexity Meter v1.4 (meter-core 1.2.0, baseline HC-2026-10-31-c) This tab starts from a short essay Bob shared.…
Comparing SWMM Models with AI 01 Nov 2026
How to use AI to run, check and compare engines without fooling yourself. Over the past year I have built hundreds of apps with AI. The lesson that matters: AI makes comparisons cheap, so the checks have to be strict. My rules for any comparison: the same input file, .out … Read…
ICM InfoWorks and #SWMM6 01 Nov 2026
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,…
SWMM5 and ICM InfoWorks 01 Nov 2026
The same network in two engines, with the Ruby scripts and apps that compare them. I spent 18 years as Product Sector Leader for InfoSWMM and InfoSewer at Innovyze, and I have written more than 440 Ruby scripts for InfoWorks ICM. This page shows how SWMM5 and ICM differ on ……
Inside #SWMM6 01 Nov 2026
OpenSWMM 6 from the source code up: new solvers, 2D, plugins and the GUI. OpenSWMM 6 is the open successor to EPA SWMM5, built by Caleb Buahin and the OpenSWMM team at HydroCouple. I don’t write the engine. I build apps that open it up, run it next to SWMM5 … Read the rest
Inside #SWMM5 01 Nov 2026
How EPA SWMM 5.2.4 computes runoff, routing and everything between, one app at a time. Each app here opens one part of EPA SWMM 5.2.4: the source file, the equation and the numbers it produces. Many of them run the real engine, compiled to WebAssembly, in your browser. The…
SWMM History: SWMM1 to SWMM6 My Version 01 Nov 2026
The engines from 1971 to now, rebuilt and running in your browser. SWMM began in 1969 to 1971 as an EPA project with Metcalf & Eddy, the University of Florida and Water Resources Engineers. I went to Florida in 1973 to work on it, and I have worked on SWMM … Read the rest
BobSWMM Lifetime Topics on #SWMM 01 Nov 2026
More than fifty years of SWMM, organized six ways. Pick the question you have. Each topic page gives you posts to read, apps to try, an example to work through and the code behind it. The order runs from where SWMM came from, through the inside of SWMM5, to ICM, … Read the rest
Fixing EPA SWMM 5.2.4, One Proven Defect at a Time = Hydrocouple Review 20 Oct 2026
Fixing EPA SWMM 5.2.4, One Proven Defect at a Time The rounded-bottom bug, how far it reaches, and a fixed 5.2.4 built from the HydroCouple code review Prepared for Robert (Bob) Dickinson · October 19, 2026 In October 2026 Caleb Buahin set an AI agent on EPA SWMM 5.2.4 and ……
Claude Chat App for SWMM Enablement 18 Oct 2026
SWMM ENABLEMENT · TOOLING NOTE Claude Chat Archive How the single-file searchable archive of three years of conversations is built and how it works Robert Dickinson · Build of 14 October 2026 · Document written 18 October 2026 The archive is one HTML file. Open it with a…
From a SWMM5 or SWMM6 model set to a finished PDF report: 18 Oct 2026
SWMM PDF WIZARD How It Works From a SWMM5 or SWMM6 model set to a finished PDF report: the file readers, the report layout, the pdfcraft engine in the browser, and the bridge your other apps use. App version SWMM PDF Wizard 1.0.0 PDF engine pdfcraft-cli 0.8.0 (commit 9e5b70d, 16…
How the Control Section Lab works: a reference solver, two SWMM engines, and the InfoWorks ICM rules 18 Oct 2026
The Water Decides Told in the manner of Isaac Asimov’s science essays Robert (Bob) Dickinson · SWMM Enablement App version 1.1 · 17 October 2026 Engines: EPA SWMM 5.2.4 and OpenSWMM 6.0.0-alpha.4 (swmm6_rel 64d517f), both compiled to WebAssembly Units: US customary (ft, s, cfs)…