Monday, January 10, 2011

Five Gallons At A Time: Water Chemistry, Part II

The content of this page was updated on 9/12/2012.

If you're looking to keep things simple, either of these two water treatments should get your mash and sparge pHs in the right ballpark using Madison city water:

To brew an amber ale, one option would be to add 0.9 g of CaCl2, 0.6 g of CaSO4 and 0.9 g of slaked lime (aka pickling lime) to each gallon of water you use for mashing and sparging, plus 0.4 mL/gal of 88% lactic acid - a common strength sold at homebrew shops - to the mash water alone. The other option would be to forgo the mineral salts, add 1.9 mL/gal of 88% lactic acid to the total water volume, and add and additional 0.3 mL/gal of lactic acid to the mash water. If you choose the lime treatment, you should treat your water the night before you brew so the precipitates settle to the bottom of your vessel and you can leave them behind. Lactic acid doesn't precipitate solids, so you can perform lactic-only treatments on brewdays. If you use CaCO3, omit it from the water treatment and add it directly to your mash. Whether you choose lactic acid or slaked lime, make sure you mix everything well when you add the compounds.

You may wonder why I didn't create different treatment regimes for malty and hoppy beers. In my opinion, the popular claim that gypsum (CaSO4) accentuates hop character is total garbage. Because gypsum imparts a sulfury character to beer, I only use it for two purposes:

1. Making beers that taste like they were brewed at Fuller's.
2. Adding calcium when I don't want to add any more chloride (from CaCl2).

If you prefer gypsum over CaCl2, simply replace a given weight of CaCl2 with the same weight of gypsum. I'd probably flip the two values for English ales, but you can use 100% gypsum if you're feeling saucy.

Finally, I add metabisulfite to drive off any chlorine or chloramines (chlorine with ammonia added to make it less volatile) that may have been added to the water by the city. I don't believe Madison uses chloramines, which is good for us, but it's becoming more common and may arrive here someday. Half of a crushed campden tablet is enough to treat ten gallons of water, as is 300 mg of sodium metabisulfite or 350 mg of potassium metabisulfite. If you filter your water with active carbon, you don't need to worry about this at all.

Up next: a basic overview of how water chemistry affects mash pH, which you can read here.


  1. Hi Joe,
    Thanks for the post. When adding the brew salts along with the slaked lime before heating, do you run the risk of the salts settling as well, or will the gypsum and CaCl remain suspended in solution? Would it be better to add the salts separately, directly to the mash?

  2. Slaked lime combines calcium and carbonate ions to create calcium carbonate (chalk), which drops out of solution because it isn't very soluble in water. The reaction needs calcium to work and a lot of the calcium will be supplied by the CaCl2 and gypsum, so you need to add everything at once. The salts are soluble in water, so they'll dissolve and not settle out.

  3. Joe,

    Should the units of "CaCO3 Directly to Mash" be "g/gallon"?

  4. Joe,

    I tried this method for the first time today and it worked great! Thank you so much for this and all of your articles here.


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