A fast, browser-based modeling environment built on the EPANET 2.3 engine. Open WaterCAD and WaterGEMS models directly, eliminate pipe-count restrictions, and make modeling accessible to your entire team.
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Bentley's OpenFlows suite (WaterCAD and WaterGEMS) has extensive modeling depth, especially for engineering teams embedded in MicroStation or complex multi-platform CAD environments. For specialized workflows and enterprise configurations, it has long been an industry mainstay.
However, Bentley's pipe-count licensing model creates unnecessary operational friction. Sizing a license for 100, 1,000, or 5,000 pipes means engineering teams must predict network expansion in advance, often forcing utilities to trim peripheral mains or pay for a $16,000+ unlimited seat just to model an all-mains network.
epanet-js removes model size limits entirely. Whether you are running a 50-pipe subdivision or a 100,000-junction regional network, the software runs with full capabilities across every plan—even the free tier. Running local-first in any modern web browser, it lets you build networks, check fire flows, allocate demands, and test scenarios instantly on Mac, Windows, or Linux without heavy local installations.
A practical breakdown of platform requirements, network scaling, and licensing costs.
| Category | epanet-js | WaterCAD / WaterGEMS |
|---|---|---|
| Platform & OS | Cross-platform (Browser) Mac, Windows, Linux | Windows desktop only standalone or inside MicroStation, AutoCAD, ArcGIS Pro |
| Network size limits | No pipe limits on any plan | Tiered by pipe count 100 / 1,000 / 5,000 / unlimited |
| Hydraulic engine | Standard EPANET 2.3 official Toolkit 2.3.5 | EPANET-derived with Bentley numerical extensions |
| Opens WaterCAD & WaterGEMS models | Direct import retains scenarios & custom attributes | Native |
| Opens and exports standard .inp | ||
| Extended period simulation (EPS) | ||
| Pressure-dependent demand (PDD) | ||
| Multi-species water quality (MSX) | ||
| Fire flow & hydrants analysis | ||
| Scenario management | ||
| GIS & data import | Shapefile, GeoJSON, CAD | ModelBuilder Shapefiles, Geodatabases, Excel, ODBC |
| Open-source codebase | ||
| Starting cost | Free tier Pro from $950/yr | $982/yr capped at 100 pipes; unlimited is $16,137/yr |
Open Bentley model files directly with scenarios, operational controls, and custom attributes intact. You can view, edit, and simulate existing networks without an .inp export intermediate.
Every plan—including the free tier—handles models of any scale, from a 200-pipe rural scheme to a 100,000-junction all-mains network. You never face an unexpected upgrade bill because a model expanded.
The free plan includes the full EPANET 2.3 engine with no node or pipe limits. Pro is $950 per year—eliminating the single-seat bottlenecks of legacy licenses.
You don't need to choose between tools or migrate legacy data manually. epanet-js opens WaterCAD and WaterGEMS models directly, bringing over your base layout, operational scenarios, and custom attributes intact. With no pipe-count caps on the free tier, you can immediately test how your actual network performs in the workspace.
Deliverables remain completely flexible. When working for a client that requires a Bentley-formatted deliverable, you can perform your builds, calibrations, and scenario testing rapidly in epanet-js, then export standard EPANET files for seamless import back into WaterCAD or WaterGEMS. You keep the speed and team-wide access of epanet-js while fulfilling contract specifications.
Frequently asked questions about moving between epanet-js and Bentley's water modeling tools.
How epanet-js compares with Autodesk's GIS-integrated platform on setup speed, GIS management, licensing, and standalone use
Where WS Pro's engine and multi-user database shine, and where epanet-js is the faster, lighter choice for distribution networks
Import an existing WaterCAD or WaterGEMS model and see how your network runs in a lightweight, browser-based environment—with zero pipe limits and no desktop installs.
No login needed