My Water

Many words have been written about water in brewing.  Everything about water is pretty much known, how it behaves in the presence of malt, its impact of chemistry and flavor. Unfortunately water is one of those topics that many brewers struggle to understand. In this post I am going to talk about the local water (Southwest Pennsylvania) and how I approach its modification for brewing.

First I want to give credit to two sources that have taught me about 95% of what I know about water.  The first is John Palmer, whose website How to Brew is a fantastic resource and includes a free, simple, water chemistry spreadsheet.  The second in Kai Troester, whose even more detailed website and blog are full not just of information but experiments he has conducted.  My hats off to both, and thanks for the help.

The first thing about water is knowing what is in your brewing water.  When I became interested in the topic there were not many resources available to learn about the local water supply.  A few years back I called the local water company and found a very helpful person who sent me three or four years of local testing records.  While this was very useful, it was explained that some of the parameters were only tested once per year and for some measurement (sulfate, for example) there was some significant variation. But not having access to better information, I did my best with what I had.

Today, with the growing popularity of brewing, water test kits have become much more available.  A simple one that I use is made by API and is sold for use in keeping aquariums.  This kit is available for less than ten dollars and allows for quickly measuring two important parameters: water hardness and carbonate levels.  These two parameters are key to understanding and predicting your mash pH.  There are kits available which also measure sulfate, and places such as Ward Labs will test a sample of your water for a small fee. If you are a serious home brewer there is not much excuse for not knowing your water.

Here is a breakdown of the typical minerals and ions found it Pittsburgh area water:

Calcium 30 ppm
Magnesium 10 ppm
Sodium 25 ppm
Chloride 30 ppm
Sulfate 75 ppm
Alkalinity 70 ppm

This is really nice brewing water, as most of theses levels are at or below the minimum required (and it is always easier to add the required minerals, versus having to dilute with distilled water in order to reduce concentrations).  The other not so obvious but equally import factor is this water’s low residual alkalinity (in the range of 35).  What the heck is residual alkalinity and why should you care?  Here is my quick and dirty explanation:

For a number of reasons, the ideal mash pH is 5.3 to 5.7.  When water and malt are mixed, chemical reactions occur with the calcium and magnesium in the water. These reactions tend to lower the mash pH (make it more acidic, which is a good thing).  Darker roasted and crystal malts tend to lower the pH more than lightly kilned malts. This tendency to a lower pH is offset by the alkalinity of the water.  The residual alkalinity is the measure of a water’s tendency to lower mash pH.  It is calculated from the water’s calcium, magnesium, and alkalinity levels.  Grain bills with high levels of roasted/crystal malts tend to require water with higher residual alkalinity (RA =100 and up) whereas very pale beers needs a lower residual alkalinity to allow the pH to drop low enough (RA less than 0).

One can see that a RA of 35 is a very happy medium, very suitable for pale ales and other medium colored beers.  Only the most pale beers may require acid malt or an acid addition to bring their pH in line.  Compare this to two other extremes in brewing water: Dublin, the home of stout, has a RA >250.  Pilsen, the Czech home of the pilsner beer has a RA of probably about 10.

If there is a downside to this it is the fact that the mineral levels, especially sulfate, are on the low side for hoppier beer styles.  Note this consideration is only about beer flavor and not about mash pH.  Extract brewers should have low concern about residual alkalinity but should pay attention to sulfate, chloride, and sodium levels. Note that besides pH, the calcium can impact the yeast performance.  At 30 ppm the calcium in my water is a little low, and an extract brewer might still benefit from small calcium additions.

In the next post about water I will provide specific examples of how I went about treating my brewing water.

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