Free, open-source storm sewer design — Rational method hydrology, Manning hydraulics, HGL/EGL backwater, HEC-22 inlets with bypass carryover, auto-sizing, and drawing-set schedules, on Windows, macOS, and Linux. Built by a practicing water-resources PE.
Download the latest release — Windows installer, macOS universal app, Linux AppImage.
A free, open storm-sewer design tool — hydrology & hydraulics for gravity pipe networks (Rational method, Manning, HGL backwater), an open recreation of the standard, public-domain methods used by tools such as Autodesk Hydraflow Storm Sewers.
0.9.2 · GPL-3.0-or-later · free for the world. Ships four ways: a desktop app, a command-line tool, a browser (WebAssembly) app, and an embeddable Rust/WASM engine library.
| You want… | How |
|---|---|
| To try the engine — no install | https://mf4633.github.io/stormsewer/ runs the same Rust engine as WebAssembly: quick calculators and whole-network analysis from an .ssn file, entirely client-side. The drawing and profile views are desktop-only |
| The desktop app | From the Releases page: Windows StormSewer-0.9.2-setup.exe; macOS StormSewer-macos-universal.zip (Apple Silicon + Intel); Linux StormSewer-x86_64.AppImage (self-contained — chmod +x and run) or StormSewer-linux-x64.tar.gz |
| A package manager | macOS: brew tap mf4633/tap && brew install --cask mf4633/tap/stormsewer. Windows: winget install MichaelFlynn.StormSewer (pending manifest review) |
| The command-line tool | brew install mf4633/tap/stormsewer-cli (macOS + Linux), or from Releases: stormsewer-cli-linux-x64.tar.gz / stormsewer-cli-macos.tar.gz — unpack and run stormsewer-cli <network.ssn> |
| To build it yourself (any OS) | Install Rust, then git clone https://github.com/mf4633/stormsewer && cd stormsewer && cargo build --release. Binaries land in target/release/: StormSewer (app) and stormsewer-cli |
| The engine as a Rust crate | cargo add stormsewer — docs.rs |
| The engine from Python | pip install stormsewer — Rational, Manning, HGL and whole-network analysis straight into pandas (docs) |
The web app, prebuilt downloads, the Homebrew tap, and the crate are all live. Building from source works on any OS (see
DISTRIBUTION.md).Windows and macOS builds are unsigned, so SmartScreen and Gatekeeper warn on first run; on macOS, right-click the app and choose Open.
StormSewer needs a graphics driver (Direct3D 12 or OpenGL 2.0+). Run
StormSewer --check-rendererto find out whether a machine can run it — it starts, draws, exits, and reports which renderer worked. A Windows machine with no display driver at all cannot run it; use the browser build instead. See ROADMAP.md.
- Rational method peak-flow accumulation (
Q = C·i·A) down a dendritic pipe network. - Manning open-channel / partial-flow hydraulics for circular, box, elliptical, and arch conduits — exact geometry (no table lookups): normal depth, critical depth, full-flow and maximum capacity, velocity.
- Time of concentration — Kirpich, NRCS TR-55 sheet flow, FAA; travel time accumulated pipe-by-pipe.
- HGL backwater — true standard-step gradually-varied-flow profile with
flow-regime classification (sub/critical/supercritical/pressurized), junction
losses (
H = K·V²/2g), tailwater seeding, and surcharge / adverse-slope handling. - HEC-22 structure losses — access-hole energy loss (relative size, deflection, plunging, benching), opt-in per project.
- HEC-22 inlets — grate, curb-opening, combination, and sag interception (Izzard gutter spread, frontal/side-flow efficiency, weir/orifice sag).
- Standard-pipe sizing — smallest catalog diameter meeting velocity and percent-full criteria (Hydraflow-style design checks).
- Rainfall — three-parameter IDF curves, multi–return-period sets, a frequency factor (Cf), and NOAA Atlas 14 import with automatic a/b/c fitting.
- Reports — a submittal-shaped PDF: title block on every page, ruled pipe / structure / inlet schedules, a scaled plan schematic, and a profile with real elevation and station axes, HGL/EGL, and stated vertical exaggeration. Choose the sections and the destination in the Report Options dialog.
All units are US customary (feet, seconds, cfs) unless a metric Manning/gravity constant is passed. Implementations are intentionally simple and standards-based so they can be audited against hand calculations — and VALIDATION.md does exactly that, working every number on a reference network by hand and matching the engine to six decimal places.
use stormsewer::{Network, Node, Pipe};
let net = Network {
nodes: vec![
Node::inlet("N1", 100.0, 105.0, 2.0, 0.7), // invert, rim, area (ac), C
Node::inlet("N2", 99.0, 104.0, 3.0, 0.8),
Node::outfall("OUT", 98.0, 103.0),
],
pipes: vec![
Pipe::new("P1", "N1", "N2", 100.0, 1.5, 0.013), // length, dia (ft), n
Pipe::new("P2", "N2", "OUT", 100.0, 1.5, 0.013),
],
};
// Quick check at a constant intensity (i = 4 in/hr):
let results = net.analyze_rational(4.0).unwrap();
// Full analysis (Tc → IDF intensity → design Q → hydraulics → HGL):
// let analysis = net.analyze(&idf_curve, &AnalysisOptions::default()).unwrap();See src/lib.rs for the full rustdoc, src/network.rs and src/hydraulics.rs
for the core, and examples/sample.ssn for an input file.
A command-line binary is built from the stormsewer-cli bin target:
cargo run --bin stormsewer-cli -- examples/sample.ssnThe engine runs in the browser via WebAssembly — the same validated code as the
CLI, no server. The stormsewer-wasm crate exposes wasm-bindgen functions
(manning_full_flow_circular, rational_peak, normal_depth_circular,
critical_depth_circular, kirpich_tc, tr55_sheet_flow, and analyze_ssn
which runs a full network analysis from .ssn text).
./wasm/build.sh # builds wasm/pkg via cargo + wasm-bindgen
cd wasm && python3 -m http.server # then open http://localhost:8000wasm/index.html is the working playground (live calculators + full-network
analysis, all client-side). The PDF export (printpdf) is behind the default
pdf feature and excluded from the wasm build.
cargo build
cargo test # 180+ tests: engine, I/O, GUI app, and validation suitesRequires stable Rust (edition 2021).
Correctness is pinned to hand-derived reference values, not just ranges:
cargo test --test validation # analytical checks (Manning, Rational, Tc, …)
cargo test --test worked_example # full two-pipe network vs. hand calc
cargo test --test hgl_validation # HGL backwater vs. hand calc
cargo run --example worked_example # print the hand-vs-engine comparison tableSee WORKED_EXAMPLE.md and READINESS.md.
| Path | Contents |
|---|---|
src/hydraulics.rs |
Circular open-channel hydraulics (Manning, normal/critical depth) |
src/network.rs |
Network model, Rational accumulation, HGL backwater pass |
src/hydrology/ |
Tc estimators, TR-55, IDF curves and sets |
src/design/ |
Pipe sizing, design criteria, HEC-22 inlets, review, cost |
src/io/ |
DXF, LandXML, PDF, HTML, project and .stm import/export |
app/ |
egui desktop application (plan view, editing, reports) |
examples/ |
Sample inputs and a WASM playground |
GPL-3.0-or-later — free for the world. Full text in LICENSE;
SPDX headers in every source file. StormSewer is an open recreation of standard,
public-domain methods; see PROVENANCE.md for the sources each
method implements and the clean-room basis.
Hydraflow and Autodesk are trademarks of Autodesk, Inc. StormSewer is an independent project, not affiliated with or endorsed by Autodesk.
StormSewer is free and GPL, and stays that way.
- Bugs & feature requests — open a GitHub issue; they're read.
- Commercial support, custom implementations, priority features — a DOT-specific report template, integration with your firm's workflow, training, or a feature your projects need: email support@hydrocomplete.com. Built and maintained by a practicing water-resources PE.
- Say thanks — if StormSewer saved you a submittal cycle, you can buy me a coffee, or try the browser suite at hydrocomplete.com.
Reference sheets used alongside StormSewer: storm sewer design criteria and minor loss coefficients on pe-calc.com.