Epanet-JS(macwright.com)
macwright.com
Epanet-JS
https://macwright.com/2025/07/03/epanet-placemark
23 comments
I suppose it's correct to say EPANET competes with expensive commercial offerings, but it's actually available completely free:
https://www.epa.gov/water-research/epanet
I know someone who uses it to design clean drinking water distribution systems in rural communities in Central America. They would not be able to do what they do if they had to pay for an expensive commercial licence.
Desktop EPANET is still windows-only though, so having a browser version is pretty cool.
https://www.epa.gov/water-research/epanet
I know someone who uses it to design clean drinking water distribution systems in rural communities in Central America. They would not be able to do what they do if they had to pay for an expensive commercial licence.
Desktop EPANET is still windows-only though, so having a browser version is pretty cool.
Currently the two largest vendors of hydraulic modelling software are Autodesk and Bentley. Both have taken the EPANET engine and created private forks in the 90s/2000s and never contributed back.
The commercial tools have made it easier for engineers at consultancies and utilities to build hydraulic models by integrating GIS and providing support for scenarios to compare different states of the model or future developments of a city.
Though as Tom points out, this comes at a huge price.
The US EPA does offer a simple GUI which can be used for smaller systems but without a connection to GIS, its usage has been limited.
These commercial versions have become enterprise monsters, they are very complex and expensive.
We wanted to create the right balance between what the US EPA already gives away for free and what the big vendors offer. We believe that releasing the software as FSL which transitions to MIT gives us the right head start and for the advanced features we're charging about 10% of what Autodesk and Bentley do - and for those that think that's too much, they of course can download and host their own private version too.
For those that are still curious, here are some extra links and context.
https://app.epanetjs.com/ – Try the app, it's local first and registration optional
https://github.com/epanet-js/epanet-js – Here is all the source code
https://github.com/epanet-js/epanet-js-toolkit – See how we converted the C engine to WASM
https://epanetjs.com/ – Read a landing page to see what we're doing and why, also our pricing
https://www.autodesk.com/products/infowater-pro/overview – Autodesk's product $10k/yr/user
https://en.virtuosity.com/openflows-water – Bentley's product $16k/yr/user
The commercial tools have made it easier for engineers at consultancies and utilities to build hydraulic models by integrating GIS and providing support for scenarios to compare different states of the model or future developments of a city.
Though as Tom points out, this comes at a huge price.
The US EPA does offer a simple GUI which can be used for smaller systems but without a connection to GIS, its usage has been limited.
These commercial versions have become enterprise monsters, they are very complex and expensive.
We wanted to create the right balance between what the US EPA already gives away for free and what the big vendors offer. We believe that releasing the software as FSL which transitions to MIT gives us the right head start and for the advanced features we're charging about 10% of what Autodesk and Bentley do - and for those that think that's too much, they of course can download and host their own private version too.
For those that are still curious, here are some extra links and context.
https://app.epanetjs.com/ – Try the app, it's local first and registration optional
https://github.com/epanet-js/epanet-js – Here is all the source code
https://github.com/epanet-js/epanet-js-toolkit – See how we converted the C engine to WASM
https://epanetjs.com/ – Read a landing page to see what we're doing and why, also our pricing
https://www.autodesk.com/products/infowater-pro/overview – Autodesk's product $10k/yr/user
https://en.virtuosity.com/openflows-water – Bentley's product $16k/yr/user
Very neat looking tool.
Do you expose an api to set and get network information like valve placement, demand at nodes or pump schedules?
In my old research group we ran a forked versions of epanet to do some of these things and there was a previous effort called oompnet that tried to bring oo into working with epanet.
If researchers can use epanet-js to give their researched algos and methods for wdn control or management, the combination could actually give Bentley a run for their money.
You might want to present this at ewri and ewra or ccwi, there are usually quite a few people working with epanet there.
Do you expose an api to set and get network information like valve placement, demand at nodes or pump schedules?
In my old research group we ran a forked versions of epanet to do some of these things and there was a previous effort called oompnet that tried to bring oo into working with epanet.
If researchers can use epanet-js to give their researched algos and methods for wdn control or management, the combination could actually give Bentley a run for their money.
You might want to present this at ewri and ewra or ccwi, there are usually quite a few people working with epanet there.
One of the two authors of epanet-js here - you can check out the source code for the app here:
https://github.com/epanet-js/epanet-js
https://github.com/epanet-js/epanet-js
This is really cool and fair play to him/them for doing this..
One thing I don't understand though is the license.
> Fully open source (MIT) after two years under our Functional Source License (FSL).
What exactly does this mean?
One thing I don't understand though is the license.
> Fully open source (MIT) after two years under our Functional Source License (FSL).
What exactly does this mean?
It grants them a two-year headspace in which licensees are prohibited to create a competing offering based on the open sourced code—so e.g. Amazon can't just take the source code and create a paid offering within AWS without contributing to upstream—at least for two years after officially licensing the software.
You can read the FSL license text here: https://github.com/getsentry/fsl.software/blob/main/FSL-1.1-...
Sounds like a reasonable tradeoff to ensure companies don't have immediate disadvantages from open sourcing their code.
You can read the FSL license text here: https://github.com/getsentry/fsl.software/blob/main/FSL-1.1-...
Sounds like a reasonable tradeoff to ensure companies don't have immediate disadvantages from open sourcing their code.
I was under the impression that municipalities use GIS systems to contain "everything" (sewers, water and gas pipes, and the electricity,telephone,fiber cables etc)
Is that just a pipe dream (no pun intended) or do those lack the simulation part ?
The GIS system is generally the base for a hydraulic model. You use that data to build a connected graph structure that the hydraulic engine, EPANET, uses to run calculations to figure out the pressure at the nodes and also flow rates in pipes.
There is also a water quality component where you can calculate the age of water in the system or chemical, such as chlorine, or other by-products you may or may not want in the system.
The US EPA site goes into technical details on what the engine can do [0], but the vast majority of modeling is done as part of a water master plan for a water utility.
A water utility will build a hydraulic model of their network and calculate and model the growth of their city over a 30-year period. The model will highlight areas of concern, generally low pressure, and the water utility can propose new infrastructure like larger pipes, tanks, or pumps, and will schedule future capital works to keep service levels acceptable.
They generally repeat this process every 3–5 years, rebuilding the model and rewriting their master plans. Here is an example of a master plan by the City of Kyle [1].
Generally, a water utility is proposing tens of millions of capital works, if not more. So traditionally, the high price tag has just been accepted. But obviously, this doesn't scale down to smaller utilities, and normally consultants will do the work on their behalf, including holding the right software license.
[0] https://www.epa.gov/water-research/epanet
[1] https://www.cityofkyle.com/media/69766
There is also a water quality component where you can calculate the age of water in the system or chemical, such as chlorine, or other by-products you may or may not want in the system.
The US EPA site goes into technical details on what the engine can do [0], but the vast majority of modeling is done as part of a water master plan for a water utility.
A water utility will build a hydraulic model of their network and calculate and model the growth of their city over a 30-year period. The model will highlight areas of concern, generally low pressure, and the water utility can propose new infrastructure like larger pipes, tanks, or pumps, and will schedule future capital works to keep service levels acceptable.
They generally repeat this process every 3–5 years, rebuilding the model and rewriting their master plans. Here is an example of a master plan by the City of Kyle [1].
Generally, a water utility is proposing tens of millions of capital works, if not more. So traditionally, the high price tag has just been accepted. But obviously, this doesn't scale down to smaller utilities, and normally consultants will do the work on their behalf, including holding the right software license.
[0] https://www.epa.gov/water-research/epanet
[1] https://www.cityofkyle.com/media/69766
I'm no physicist, but I've worked as a software engineer on energy (and drinking water, which EPANET simulates) infrastructure network design tooling for the last six or so years. It has been my understanding that simulating and validating multimodal network designs, which take into account electricity, gas consumption, district heating, is extremely difficult.
Municipalities definitely have systems that document where everything already is under the ground (though especially in Europe there are many older cities where the data of old pipes is lacking), but for designing new energy networks, an "everything" simulation and solving model is very, very complex.
Municipalities definitely have systems that document where everything already is under the ground (though especially in Europe there are many older cities where the data of old pipes is lacking), but for designing new energy networks, an "everything" simulation and solving model is very, very complex.
Some might in fact contain everything, but the core difference is that this is a simulation engine not a GIS tool.
My first thought - is it possible to use Epanet.JS to create a browser-based SimCity-like game?
Epanet is used to stimulate water flow and pressure loss (head loss) in a pipe network so you can design a pipe network that meets your water flow and pressure requirements. It probably can be used in a city game if that game has water distribution network component.
Yes, I mean precisely using it for simulating pipe network.
I love the idea of a SimCity type game with a ton of details. Having the level of detail of simulating a water distribution system is some dwarf fortress type detail. Make sure to also add a permitting office, building permit system, and HOAs that protest your building permits.
Or a more minimalistic, where you only focus on pipes and wires.
(Compare: Railroad Tycoon)
(Compare: Railroad Tycoon)
Never heard of EPANET nor did I know that drinkable water systems had a specialized software. That's a great early hour knowledge.
So cool! I wonder if I can use this software to plan an irrigation system for my garden.
Does the simulation also work on a smaller scale?
Does the simulation also work on a smaller scale?
You can (I've used it to design an irrigation system in the Yucatan) but at small scale, a spreadsheet is probably sufficient.
At a smaller scale, the efficiencies gained from properly designing the system are not a major savings.
That said, if I had a garden with a big fountain I absolutely would try to model it in EPANET ;)
Just how fancy is your irrigation system?
That said, if I had a garden with a big fountain I absolutely would try to model it in EPANET ;)
Just how fancy is your irrigation system?
What's the business plan ?
Why don't make it like 20$ a month ?
Are your working in a company that needs this 16000$ software, so they are just happy to cut the fees and don't care about making it opensource ?
Surprised how well this worked on my 8 year old phone despite mobile support being in preview, very well done.
ne doljno!
I have absolutely no use for epanet-js, but this is so cool. Exactly what free software is supposed to do.