EPA EPANET

free (public domain) Design the Building

Free, public-domain water distribution system modeling software by the US Environmental Protection Agency -- performs extended-period simulation of hydraulic and water-quality behavior within pressurized pipe networks (pipes, pumps, valves, tanks), tracking flow, pressure, water age, chlorine residuals, and contaminant transport; provides a C Programmer's Toolkit (DLL with 50+ functions) for custom integration; the industry-standard computational engine underlying most commercial water-distribution modeling packages worldwide.

3.4 /5 composite score

Solid -- the free, public-domain industry-standard computational engine for water distribution modeling worldwide, with a C Programmer's Toolkit API enabling deep customization and integration into GIS/CAD environments; no subscription cost, an active open-source community on GitHub, and the .inp format as the de facto industry interchange standard make it the baseline for water distribution analysis; scoring reflects outstanding value and openness offset by a dated Windows-native GUI, no vendor support contract, and desktop-only delivery (no REST/CLI).

Solid

Rubric Scorecard

How we grade →

Criterion	Score	Evidence
Value for the price	5/5	free (public domain), from $0, free tier
Agent Friendliness	3/5	API: EPANET 2 Programmer's Toolkit (C DLL with 50+ functions for opening/modifying networks, running simulations, accessing results); open-source C engine on GitHub (USEPA/epanet-engine)
Ease of adoption	2/5	desktop-install, steep learning curve
Portability & lock-in	5/5	3 file formats
Interoperability	2/5	4 integrations

Visit EPA EPANET →

How we verified this: we checked EPA EPANET against its live site and an independent source — en.wikipedia.org. Nothing on this page is listed from memory. See how we grade. Verified 2026-07-05.

Evidence

File formats

Format	Direction	Support
INP	native	full -- EPANET .inp input format (industry-standard text format for water distribution models)
CSV	export	full
DXF	export	full

Integrations

ArcGIS (middleware) QGIS (middleware) InfoWater Pro WaterGEMS

Adoption

Deploymentdesktop-install

Self-serve signupyes

Learning curvesteep

Pricing detail

Free tier scopeusable

Sources

Status Changelog

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