Monday, February 6, 2012

Five Gallons At A Time: Water Chemistry Updates

The content of this page was updated on 9/7/2012.

I'm always trying to better myself as a brewer, and I've gathered a lot of new data about water and mash chemistry over the past year and a half. Some of it significantly affects how brewing water should be treated:

-The target mash pH range of 5.2-5.5 is for room temperature measurements, not mash temperature measurements.
-Some of the pH strips available at homebrew shops report values that are about 0.3 lower than the actual pHs. I was using them, which made me believe my mashes were within the target pH range when they weren't.
-Kohlbach's claim that each mEq/L of residual alkalinity will raise pH by 0.084 was for 12-Plato kettle wort, not mashes.
-Water with significant carbonic acid, such as Madison city water, requires additional slaked lime to convert carbonic acid into bicarbonate ions.
-Lactic acid does not fully dissociate at common brewery pHs

Armed with new information, I updated the series on water chemistry and consolidated it from six parts to five (woohoo!). Here are the links to the articles:

Part I (introduction)
Part II (ballpark water treatments)
Part III (factors that affect mash pH)
Part IV (bulk water treatment)
Part V (mash water treatment)

I rewrote the old articles instead of writing new ones because leaving up the old stuff, some of which was valid and some of which was outdated, would have been confusing. In addition, I wanted to leave the original web addresses intact so people who use them as references would be able to find the new information as easily as possible. I included latest revision date in the body of each post so people will know when the content has changed since the publishing dates.


  1. Thanks for the update, Joe.
    How did you come up with the Madison water alkalinity levels? I'm not seeing it in the standard report.

  2. The city publishes water quality reports for each well, which you can download at If you click on the inorganics link within the file for your particular well, it'll take you to a file that lists the water properties. The well tables are usually a year old (I'm hoping they make the 2011 versions available soon), but I think they're still better than the overall Madison report. Since I originally wrote these articles last year, the numbers in these posts are not the newest versions.


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