StormSewer

StormSewer is a free, open-source desktop program for gravity storm-drain design and analysis.

Draw the network on a scaled aerial or import it from a Civil 3D Storm Sewers .stm file, LandXML or DXF, then run the Rational method, Manning capacity for circular, box, elliptical and arch conduits, and a standard-step HGL/EGL backwater pass with junction losses and tailwater. HEC-22 inlet interception carries bypass from one inlet to the next. Auto-sizing meets velocity and percent-full criteria, and a NOAA Atlas 14 import fits your own IDF coefficients.

Reports come out as a submittal PDF with a title block on every page, ruled pipe, structure and inlet schedules, a scaled plan, and a profile with real elevation and station axes. HTML, CSV, LandXML and DXF export as well.

The methods are public domain, so the implementation is meant to be readable: every number in the report is worked by hand in the project's VALIDATION.md, and the same network was run side by side through Hydraflow Storm Sewers with every difference explained rather than hidden.

Windows, macOS and Linux installers, a browser build of the engine, a Rust crate and a Python package for scripting. Written by a practicing water resources engineer. GPL-3.0.