Delta Hydro Studio
FreemiumVerified
Browser-based hydrology and hydraulics calculators for practising engineers — no install, report-ready output.
Urban Stormwater & InfrastructureActiveRational MethodCulvert Sizing
EPA SWMM
DHS VerifiedActiveThe public-domain engine of urban drainage: dynamic-wave pipe networks, runoff, LID and water quality.
by US EPA
- Pricing
- Gov-Public
- License
- Public domain (CC0)
- Commercial use
- Permitted
- Ecosystem
- Standalone, C engine, Python ecosystem
- Platform
- Windows, Linux (engine), macOS (engine)
About EPA SWMM
EPA's Storm Water Management Model is the reference engine for urban hydrology and hydraulics: subcatchment rainfall-runoff, full dynamic-wave routing through pipes, channels, storage and controls, low-impact-development modules, groundwater interaction, and pollutant buildup-washoff — continuous or single-event.
SWMM's public-domain status is why the entire urban-drainage software industry sits on top of it: PCSWMM, InfoWorks-style suites, countless municipal spreadsheets and the whole PySWMM ecosystem. Learn the engine once and every wrapper becomes familiar. If you do urban drainage and have not opened SWMM directly, it is worth knowing exactly what the commercial GUIs are charging for.
Where it fits in the workflow
TerrainCatchmentRainfallRunoffRoutingHydraulicsMappingReporting
Alternatives to EPA SWMM
Other urban stormwater & infrastructure tools covering similar workflow stages.
PySWMM
Open SourceVerified
Python interface to the SWMM engine — step through simulations, read state, and control gates in real time.
Urban Stormwater & InfrastructureActiveSWMMPython Hydrology
EPA National Stormwater Calculator
Gov-Public
EPA's free tool for estimating site runoff reduction from green infrastructure, with climate scenarios.
Urban Stormwater & InfrastructureStableSuDS & LID DesignStormwater Design
EPA SSOAP Toolbox
Gov-Public
EPA's toolbox for sanitary sewer overflow planning — RDII analysis with the SWMM engine underneath.
Urban Stormwater & InfrastructureDormantSewer ModellingSWMM
Generate SWMM inp (QGIS plugin)
Open Source
Build and read EPA SWMM models as QGIS layers — free GIS-based SWMM model construction.
Urban Stormwater & InfrastructureActiveSWMMQGIS Hydrology
HydroCAD
Commercial
The US land-development standard for TR-55/TR-20 hydrographs and detention pond design.
Urban Stormwater & InfrastructureActiveDetention DesignTR-55