Frequently asked questions

Find on this page answers to common queries about The Geochemist's Workbench®


When was The Geochemist's Workbench® first released?

The Geochemist's Workbench® was introduced in 1991 and since then has set the standard in geochemical modeling. Many thousands of licensed copies have been installed in more than 90 countries around the world.

Who is Aqueous Solutions?

The GWB software was developed originally by the students, staff, and faculty of the Hydrogeology Program at the University of Illinois. The development team moved to the University of Illinois Research Park and works under the name Aqueous Solutions LLC. The team is supported solely by end-user license fees.

What's new in GWB 2023?

A lot is new in GWB 2023! Use SIT activity coefficients, import thermo datasets from PhreeqC, and take advantage of the thermo data editor to couple and recouple redox reactions. An all new compute engine makes the release a surface chemistry powerhouse. Plus, enjoy user equations in GSS datasheets, high-temperature Pitzer coefficients, cluster computing, and flexible input for thermo data, just to start. A must-have upgrade for every GWB user!

How do the Professional, Standard, and Essentials versions differ?

Our handy charts show the programs and features in each version. The GWB overview page outlines the features of each version, and the GWB Professional, Standard, and Essentials pages provide details.

GWB Online Academy

What is the GWB Online Academy?

The GWB Online Academy is a hub for learning to use The Geochemist's Workbench. Anyone can use it; anyone can contribute.

Who makes it?

Aqueous Solutions LLC, Maker of The Geochemist's Workbench, founded the GWB Online Academy, but it's not finished. We set it up so that anyone can contribute their expertise and experience to the geochemistry community.

Can I download slides, lesson plans, and input files to use in my course?

Visit our lesson plans page to download a set of teaching materials covering a variety of topics.

I'm an expert user of the GWB and I'd like to present training workshops in my area. Can I use your training materials?

Much of the content in our popular workshops is available on the GWB Online Academy. You're free to use it. Need training licenses? Just ask.

Can I submit my own courseware to the GWB Online Academy?

Yes, whether you teach at the introductory or advanced level, we're interested in what you have to offer. We'll acknowledge your authorship.

I'm not a geochemist, but the GWB is great for what I do. Can I submit my applications?

Our users hail from a variety of fields. We'd love to see how you solve problems with the GWB. Visit our submission page to get started.

What do I need to do to get my courseware listed?

You should prepare a set of slides and a lesson plan along with one or more input files. Check out our submission page for details.

I've compiled high-quality thermodynamic and surface reaction datasets. Can I make sure that they're available for the community to use?

We're happy to accept new sources of thermodynamic data as part of your courseware submission. With our graphical editor TEdit, it's never been easier to edit and combine datasets yourself.

Will I benefit from attending a training workshop after going through the GWB Online Academy?

Group workshops are a great complement to self-study with the GWB Online Academy. Two days of hands-on training, free of your normal distractions, makes for an effective use of your valuable time. Plus, they're a great opportunity to meet with smart geoscientists and make new friends.

I'm using the free GWB Community Edition. Can I work through exercises in the GWB Online Academy with my license?

Each lesson is marked with the specific GWB version needed to complete the exercises. If you need more capabilities, consider upgrading or request a demo.

The lesson plan I'm working through recommends I use GWB 2023. How can I upgrade my license?

You can save 50% when you upgrade to a GWB 2023 subscription. Visit our upgrade pricing page for more info.


What programs are included in each version of GWB?

Here's a handy chart that shows the programs included in each version, and what each program does.

What sources of thermodynamic data are available?

The default thermo dataset, thermo.tdat, compiled by Lawrence Livermore National Laboratories, as well as a number of other datasets are installed with the software. You can download any or all of the datasets from the thermo data page. You query the users' group about thermo datasets via the GWB forum.

I overwrote a thermo dataset. How can I restore it?

You can download any of the datasets installed as part of the GWB from the thermo data page. You can as well find links to other sources of thermodynamic data there.

How does the GWB calculate activity coefficients?

By default GWB uses the "B-dot" model, an extended form of the Debye-Hückel equation, to calculate species activity coefficients. Where the ionic strength is high, you can calculate activity using the SIT method or "Pitzer equations."

How does the GWB model sorption?

GWB can account for sorption onto surfaces using: the Kd approach; Freundlich or Langmuir isotherms; ion exchange; the double layer model of surface complexation, with or without electrostatic effects; and the triple-layer and CD-MUSIC surface complexation models. The surface complexation models support multiple conventions for polydentate complexes; 1-pKa or 2-pKa reactions; and options for site density units.

Can I model more than one sorbing surface?

You can combine as many sorption datasets as you like, and you are free to mix, for example, Kd sorption with surface complexation reactions.

Can I mix water samples in GWB?

You can mix fluids easily using programs React or GSS. In this way, you can calculate pH buffering, the dilution of contaminants, the precipitation of minerals, or the energy available to microbial communities along geochemical gradients.

Can I construct models accounting for reaction kinetics?

You can include in any reaction or reactive transport model the kinetics of (1) mineral dissolution and precipitation, (2) formation and dissociation of complex species, (3) sorption and desorption, (4) redox transformation, including the effects of enzymes and catalysts, (5) microbial metabolism and growth, and (6) gas transfer.

Over what range of temperature can I apply the GWB?

The GWB programs operate within the temperature range of the thermo dataset currently loaded. The default thermodynamic dataset thermo.tdat contains log K entries compiled along the steam saturation curve from 0°C to 300°C.

Do I need to account for confining pressure that deviates from steam saturation?

You can use a thermo dataset compiled at the pressure of interest, but hydrothermal chemists not uncommonly assume the effects of confining pressure are small compared to the uncertainty in determining log Ks and activity coefficients. Note, however, that gas partial pressures are almost invariably significant. You account for a coexisting gas by setting its partial pressure or fugacity.

Can I import flow fields generated by other flow models into X2t?

X2t can import a two-dimensional flow field from a space-delimited or tab-delimited table. The table should consist of cell-to-cell discharges. X2t can also import flow fields generated with the popular Modflow code.

Can I model reactive transport in radial or spherical coordinates?

X1t models reactive transport in a single rectilinear, radial, or spherical dimension, and X2t traces simulations in two-dimensional rectilinear and axisymmetric coordinates. The GWB does not currently include a three-dimensional simulator.

Why do the charge imbalances I calculate with GWB 2023 differ by a factor of two from the imbalances I figured with GWB8?

GWB8 calculated charge imbalance according to Zhu, C. and Anderson, G. (2002), Environmental Applications of Geochemical Modeling, Cambridge University Press, 284 p.
{charge balance = 100 * [(sum cations - sum anions) / (sum cations + sum anions)]}GWB9 and later releases, at the request of users, use the calculation presented by Weight, W.D. (2008), Hydrology Field Manual, McGraw Hill, 751 p.
{charge balance = 100 * [((sum cations - sum anions) / (sum cations + sum anions)) / 2]}


Which version of the GWB best suits my needs, Professional, Standard, or Essentials?

You'll find lots of useful information on the overview page and comparison charts, and the pages for the GWB Professional, Standard, and Essentials versions. You can also contact our sales staff at or by calling 217-531-1206 during normal business hours.

On what versions of Windows does the GWB run?

GWB 2023 and GWB12 run on Windows 11 and 10.

I'm having trouble installing and running my copy of GWB. Whom can I contact for help?

Please visit our troubleshooting page and you should be up and running in a jiffy. If you need further assistance, please contact

How can I get help installing a network floating license?

To install a network floating license, please visit our installation guide and troubleshooting page. If you need further assistance, please contact

Can I run the GWB on a Mac?

Many of our users have found success running GWB on a Mac using a Windows emulator such as Parallels Desktop or a dual boot configuration.

How do I install and activate the GWB software?

The sales staff will provide you with a download link and an activation code when you license or demo the software. Install the software by clicking the link and following the prompts. To activate, go to the Windows Start menu and launch the GWB dashboard by choosing “The Geochemist's Workbench”. Move to the Support tab and click Activate GWB. In the space provided, paste your activation code and click Activate.

How do I move the GWB software to another computer?

First, deactivate the GWB on the computer on which it is currently activated. To do so, open the GWB dashboard on that computer, move to the Support tab, and click Activate GWB. Next, select your activation code and click Deactivate. You are now free to install and activate the software on a different machine. You can move a license a limited number of times each year.

How can I receive help setting up or trouble-shooting my models?

Please post queries to our online forum.

What versions of GWB are currently supported?

Aqueous Solutions currently supports GWB releases 2023 and 12. Releases 11 and earlier are outdated and no longer supported.

I upgraded my Windows OS. Why does the GWB no longer work?

GWB 2023 or GWB12 are the preferred releases for Windows 11 and 10, and GWB10 or later is required for Windows 8.1 and 8.

Can I use the GWB without an internet connection?

Yes, paid versions of the GWB can be run without an internet connection. Before you can use the software for the first time on any computer, you will need to activate your license. If you do not have an internet connection, please follow the procedure for offline activation.

Why do I receive the error “This activation code is already activated on as many computers as allowed”?

Each license of the GWB is limited to use on one machine at a time and must be deactivated before being activated on a new machine.

Whom can I contact for help with payments and billing?

Please contact

Documentation, training, and consulting

I just want to make a diagram. Can you show me how?

The tutorials page contains concise step-by-step instructions for making a variety of diagrams, tracing reaction paths, running reactive transport models, and much more. The diagrams page holds a gallery of diagrams produced using the GWB. Click on the icon below a diagram to download an input file for the corresponding GWB app, pre-configured to compute that diagram. There's a movies page, as well.

Where can I find fully-worked examples of GWB runs?

Open pdf copies of the User's Guides from the Support tab of the GWB dashboard, the Help tab of any GWB app, or from the documentation page. Consult the Geochemical and Biogeochemical Reaction Modeling text for many more examples. And check out the GWB Online Academy, a self-guided course in geochemical and reactive transport modeling.

How can I get hardcopies of the User's Guides?

You can download pdf copies of the guides and cover art, and let your favorite copy shop print and bind the manuals for you.

Where can I learn about the theory and practice of reaction modeling?

The textbook Geochemical and Biogeochemical Reaction Modeling, written by the principal author of GWB and published by Cambridge University Press, is available in hardback, paperback, and eBook editions directly from Cambridge.

Do you offer short courses or workshops?

Yes, we present a series of instructor-led, hands-on online workshops. See our workshops page for details, or contact

Do you offer on-site training?

We can save your organization time and money with private training courses, either online on on-site. Contact to request more information.


Is Aqueous Solutions hiring?

Aqueous Solutions is always interested in seeing the resumes of extremely talented application programmers and geochemical modelers.