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! Incorporate solid solutions in your models, use SIT activity coefficients, import thermo datasets from PhreeqC and EQ3/EQ6, 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. And GWB Professional now includes the amazing ChemPlugin self-linking software object at no extra charge!

How does GWB Community Edition differ from the Professional, Standard, and Essentials versions?

Our handy charts show the programs and features in each version. Please visit the main GWB website for detailed information about the paid versions of the GWB.


Am I eligible for a free download of GWB Community Edition?

The entire aqueous chemistry community may download the Community Edition at no cost.

I'm a university professor that would like to use GWB Community Edition in my class. Am I eligible for an academic discount on GWB Professional, Standard, or Essentials?

Please see the academic page for qualifications.

My GWB Community Edition license expired. Can I get a new copy?

Licenses last for up to a year, after which you will need to download a fresh copy. We'll contact you and remind you when it's time to reapply.


Can I upgrade my copy of GWB Community Edition to the Standard or Professional version?

Yes, please move to the Subscription pane on the GWB dashboard or contact for a quote or an academic discount.

How soon after I place an order will I receive the software?

You will be up and running within minutes. After you check out of our online store, you'll receive email containing a link for downloading the GWB installer, as well as an activation code. Install the software, enter the activation code, and you will be ready to go.

Can I try the software before I buy?

Yes. Please visit the main GWB website to request a demo copy.

How can I get a formal quote for purchasing a license, upgrade, or training?

Please request a quote from the main GWB website or contact

Am I eligible for an academic discount?

Please see the academic page for qualifications.

Should I wait for the next release?

When you subscribe to the GWB, you have access to new features as soon as they are available, so there is never any reason to wait.


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; the datasets are also available for download from the thermo data page. You can query the users' group about sources of thermodynamic data via the GWB forum. Or, use the amazing TEdit editor to import thermo databases from PhreeqC and EQ3/EQ6.

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 easily mix samples stored in a GSS spreadsheet. Or, upgrade to GWB Standard and use program React to simulate mixing processes. 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?

Upgrade to GWB Standard or GWB Professional to 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.

Why do the charge imbalances I calculate with the GWB differ by a factor of two from the imbalances I compute by hand?

The GWB uses the calculation technique 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]}

Some people prefer to figure 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)]}


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. How can I get help?

Please visit our troubleshooting page and you should be up and running in a jiffy. If you need further assistance, consult the GWB Community Forum and, if necessary, post a query there.

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?

When you check out with the GWB Community Edition in your shopping cart, you will receive a download link and an activation code by email. 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, enter 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 troubleshooting my models?

Please post queries to the GWB Community Forum.

Can I use the GWB without an internet connection?

No, you will need an internet connection to activate the GWB Community Edition of the software.

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

A GWB Community license may be installed on two machines at a time and must be deactivated before being activated on a new machine.

Documentation, training, and consulting

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

Please visit the main GWB website for more tutorials and to browse the movies and additional diagrams you can produce when you model reaction paths and reactive transport with GWB Standard or GWB Professional.

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 private 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.