Credits
A list of the people and institutions whose work we are standing on, with enough detail that you can go and read about them rather than take our word for it. We owe EPANET the largest debt of all; it has a page of its own.
The United States government, and the people who fund it
EPANET was paid for by American taxpayers and given to the world for nothing. Under 17 U.S.C. § 105, a work prepared by a federal officer or employee as part of their duties cannot be copyrighted. So EPANET has no owner to ask, no fee and no permission to seek: it is public domain in the United States by operation of law, and distributed to the world on that basis.
That is an extraordinary thing to have done, and it is a gift rather than a background condition. A working engineer anywhere on earth, in a country that pays no American taxes, can model a water system tonight because of a decision made in a United States federal agency.
The Environmental Protection Agency, and Lewis A. Rossman
EPANET was created by Lewis A. Rossman for the EPA's water research programme and first appeared in 1993, alongside a formal report on the EPANET water quality model. EPANET 2 followed, and version 2.2 was the last release EPA itself made. It is used by utilities, consultants, regulators, and universities worldwide, and its computational engine sits underneath a great many other products, ours among them.
We have never contacted the EPA and we are not asking them to notice us. The gratitude is stated here, publicly, because that is the only form of thanks a public-domain gift admits of.
Open Water Analytics
EPANET's development continued in the open after EPA's 2.2, as a community effort in collaboration with EPA. Open Water Analytics released EPANET 2.3 on 2024-07-17 and 2.3.5 on 2025-02-20. 2.3.5 is the engine our software runs. Every volunteer who has filed an issue or a fix in that repository has, without knowing it, fixed something for us.
Everybody who extended EPANET before we did
For thirty years, people have been wrapping, porting, rebuilding, teaching and
arguing about this engine, mostly for nothing and mostly on their own time. The
graphical front ends, free and commercial. The hydraulic solver. The university courses
that taught a generation to read an .inp file. The people answering the
same file-format question in public for the tenth year running.
We mention them together because the list is longer than we know and we would get it wrong. What we can say is what it cost them and what it cost us: they did that work before the age of AI, in evenings and weekends and unpaid hours, and it is what made it possible for one semi-retired engineer with an AI to build this. That is not a boast about us. It is the measure of what they left lying around for somebody to pick up, and the reason the polite thing to do with it is to give ours away too.
The software and services we depend on
These are the third-party pieces the network editor uses. The first four are vendored, meaning a copy travels with the software rather than being fetched from somebody else's server while you work.
- epanet-js, the browser build of the EPANET engine. MIT licensed, © Luke Butler, wrapping the MIT-licensed OWA-EPANET engine and compiling it to WebAssembly. It is the single piece of code that makes an EPANET run possible inside a web page with no server, and it is the reason this project could be built by one semi-retired engineer rather than by a team.
- Bootstrap 5.3.2, MIT licensed, © 2011-2023 The Bootstrap Authors. The layout this software is built on.
- Colour schemes for maps, Apache License 2.0, © 2002 Cynthia Brewer, Mark Harrower, and The Pennsylvania State University. See the Cynthia Brewer entry below.
- viridis, magma, inferno, and plasma, released CC0 by Nathaniel J. Smith, Stefan van der Walt, and (for viridis) Eric Firing. github.com/BIDS/colormap
And two services the editor can call out to over the network. Both are off until you turn them on, each asks its own permission, and a tile request tells that service where you are looking:
- OpenStreetMap contributors, whose map of the world is the ground under a geographic project, and whose Nominatim service answers a place-name search. Map data © OpenStreetMap contributors.
- Mapbox, for satellite imagery and for the terrain elevation data a node can read its ground level from.
Cynthia Brewer, and the people who made maps readable
A network map is worth nothing if a reader cannot tell the classes apart, and much of the work of making that possible was done by cartographers rather than by engineers. Cynthia Brewer, a geographer at Penn State, published her colour scheme advice in 2002 with Mark Harrower and Penn State. The schemes are designed per class count and tested for photocopying, for projection and for colour-blind readers, which is why a five-class pressure map is legible at all. The International Cartographic Association gave her the Carl Mannerfelt Gold Medal in 2023.
Her schemes ship in our software under the Apache License 2.0, which fixes the wording of the acknowledgement below. It is the license's text, not ours:
This product includes color specifications and designs developed by Cynthia Brewer (http://colorbrewer.org/).
EPANET's own interface
It is customary in this field to describe EPANET's user interface as dated. We decline to. It is the interface that taught most working modellers what a network model is, and ours is informed by it deliberately, item by item, as the first of our disclosures says.
Richard M. Stallman, and the Free Software Foundation
The Free Software Foundation released version 3 of the GNU General Public License on 2007-06-29. It is what our software is published under, and the instrument by which what we publish stays published. We did not have to design that mechanism; somebody else spent decades on it and gave it away too. Whether it is the right choice for a project this dependent on public-domain work is an open question, and the second of our disclosures is where we admit it.
And the people whose names we do not have
The engineers who published Net1, Net2, and Net3 as example networks, which is what anybody testing an EPANET-compatible program checks against first. Everyone who has ever answered a question about the file format in public. Anyone who has reported a bug to us, or corrected a translation, in any of 27 languages. If your work is in here and your name is not, that is our failing and we would like to fix it.