Wednesday, January 5, 2011

Five Gallons At A Time: Water Chemistry, Part I

The content of this page was updated on 8/19/2012.

All-grain brewers: did you know that pH is just as important as temperature for mashing and sparging? It's true! You already know that alpha amylase and beta amylase, the malt enzymes responsible for converting starches into sugars, work best at temperatures between 149 and 158 degf. They also work best when the pH is between about 5.2 and 5.5*. If your mash pH is too far out of that range, your runoff gravity will suffer. If the pH of your grainbed is too high during sparging, you could extract excessive tannins.

Surprisingly, a lot of craft brewers don't pay much attention to pH. I'd wager the reasons are twofold:

-The underlying water chemistry is extremely complicated.
-Mash pH tends to work itself out, as long as the mash water is low in carbonates.

Unfortunately, Madison's municipal water is high in carbonates. Carbonates raise mash and sparge pHs, so brewers 'round these parts should strive to get rid of them. In the next few weeks, I hope to show you a few simple ways to do just that. Afterward, I'll outline some calculations that will either bore you to death or help you fine-tune your water treatments for specific recipes**. The next article in this series is here.

*When measured at room temperature, which you should always assume unless I specify otherwise.

**I'm not a water chemistry expert like A.J. deLange, who probably has nightmares about people like me giving advice on the subject. My calculations work well in my home brewery, but accounting for all of the chemical reactions and how they're affected by things like pH, time, temperature, molecular concentrations and the partial pressure of atmospheric CO2 (seriously) is way over my head. Throughout this series of posts, you should take my geekery with a grain of salt.


  1. Whenever I tour a brewery, I always ask about their water chemistry and if/how they treat their water. Mainly I'm curious if they 1) care, 2) treat it the same no matter what the recipe is, or 3) actually adjust it based on the brew at hand.

    Without knowing exactly what specific water profiles are, it always surprises me when a brewery, such as Lakefront, uses straight city water with no adjustments at all, no matter what the recipe.

  2. Breweries in Milwaukee like Lakefront very likely use water that was drawn from Lake Michigan. Much different than what we have around here which is water drawn from limestone-laden aquifers.

  3. Garrett, I agree with you that Lakefront is kinda bland. Maybe there lack of water treatment might be the reason why.

  4. They for sure use city water with no adjustments, as that's what tour people have told me on multiple occasions (for what that's worth). I didn't say that Lakefront is bland, I'm just surprised that they use one water profile for the myriad of recipes they do. In my opinion, they make them all work.

  5. Mark's point about Lake Michigan is the reason why. Surface water is typically low in minerals, including carbonates, which makes Milwaukee a good example of a place where mash pH tends to work itself out. It's not perfect in every situation, but a stout made with untreated surface water will perform much better in the brewhouse than a Pilsner made with untreated groundwater.


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