Water Profiles for a Westvleteren 12 Clone Recipe

One of the last things I worry about in brewing is water profiles. I'm fortunate to live in the Seattle area where the water is naturally soft, so there is a wide array of light-colored beers that I can brew with tap water, without a second thought, and without any treatment other than to remove the chlorine. For a few things like IPAs and stouts I can add a tablespoon of gypsum per seven gallons of water and be good to go.

Having brewed one Westvleteren 12 clone that wasn't as close as to the original as I wanted once before, I'm being more strategic the second time around. So water profiles are worth some study. Brew Like A Monk (BLAM) reports that Westvleteren has a water profile that is not great for brewing, so they treat their water because it is too high in bicarbonates, sodium, sulfate and chloride:

Westvleteren Water Profile
Calcium (Ca+2): 114
Bicarbonate (HCO3-): 370
Magnesium (Mg+2): 10
Sodium (Na+): 125
Sulfate (SO4-2): 145
Chloride (Cl-): 139

As with everything else Westvleteren, the actual treatment and the resulting water profile is a closely guarded secret. But according to BLAM, Chimay has a nearly perfect water profile for Belgian Dark Strong Ale, and might be what Westvleteren aims for when they treat their own water.

Chimay Water Profile
Calcium (Ca+2): 96
Bicarbonate (HCO3-): 287
Magnesium (Mg+2): 4
Sodium (Na+): 6
Sulfate (SO4-2): 32
Chloride (Cl-): 13

I'm on the other side of the water treatment line, and need to 'harden' the local water so I get the Calcium and Bicarbonate levels up high enough for brewing the dark beer I want to clone:

Seattle Water Profile
Calcium (Ca+2): 10
Bicarbonate (HCO3-): 20
Magnesium (Mg+2): 0
Sodium (Na+): 1
Sulfate (SO4-2): 3
Chloride (Cl-): 3

Brewing Salt Additions for Seattle
Chalk (CaCO3): add 11 grams, or 1 scant tbsp
Baking Soda (NaHCO3): add .75 gram, or 1/8 tsp

Adjusted Water Profile
Adding almost a tablespoon of chalk and an eighth of a teaspoon of baking soda brings the Seattle water profile within a couple of points of the Chimay water profile. An alkalinity of 150 to 300 ppm is ideal for dark beer, so we are right where we want to be.

I was very pleased to see that I got as close as I did with the example above. If you're trying get your local water profile dialed in, don't worry about hitting the target exactly. You only need to be in the general ballpark. Even when you get your local water report, it's not chiseled in stone, it will vary from year to year, so there is no guarantee that the water coming out of your tap today exactly matches the water report from last year, or from years gone by; which means that you can't adjust it with absolute accuracy anyway.

If you're interested in adjusting your local water, Brewers Friend has a good water calculator here, a list of water profiles for various cities here, and a good discussion of water chemistry here. For a much more in-depth discussion of brewing water chemistry, have a look at the Bru'N Water Knowledge Page. There is also a free downloadable Bru'N Water spreadsheet. Just don't make yourself crazy by adding minute amounts of half a dozen different chemicals every time you brew. As long as your water profile is in the general ballpark for the style, your beer will be just fine. And even if it isn't there's a pretty good chance that you can brew a great beer anyway.