OpenSWMM 6 User Guide (refactored engine)#

Note

These guides cover the OpenSWMM 6 refactored engine at openswmm.engine. If you are looking for the original EPA SWMM 5.x solver — preserved verbatim for backward compatibility — see Legacy SWMM 5 — Compatibility Layer.

The User Guide is the canonical “how do I do X?” reference for the modern openswmm.engine API. Every page follows the same layout:

  • Class signature — the constructor and how the class fits in.

  • Key methods — grouped by purpose (geometry, state, forcing, …).

  • End-to-end example — a runnable snippet covering the typical workflow.

  • Common recipes — short snippets for everyday tasks.

  • Bulk arrays — the numpy-friendly accessors (*_bulk).

  • EngineState requirements & exceptions — what’s legal when, and what each method raises.

Newcomers, start with Installation, Quickstart, then Concepts & engine lifecycle.

Running a simulation#

Domain access#

The “what’s the depth of node J1 right now?” surface. One page per domain.

Forcing & control#

Inject runtime inflows, override rainfall and time-series, fire control actions.

Water quality#

Pollutants, landuse, buildup/washoff, treatment.

Outputs#

Reading the binary .out file, hot-start save / restore, mass balance, accumulated statistics.

Specialised topics#

Build a model from scratch in Python; mutate an open model in place; configure complex hydraulic infrastructure; spatial / CRS handling.