Tuning In to Water Profiles

I have never written extensively about brewing water profiles and cannot knowingly comment about why this topic is usually addressed by reviewing the water profiles of historically important brewing centers. But I think I have a pretty good idea why this has been the approach and will answer your question from an assumption about the why. Quite simply, breweries historically brewed beers that worked well with local waters and the topic of brewing water followed this tendency. The fascination and exploration of beer style is a relatively recent development in the history of beer, and part of this process has been reviewing brewing water and trying to determine the best water for a particular style. In fact, the knowledge that we take for granted today about water chemistry is very recent in the history of brewing and goes far beyond the knowledge of most brewers as recently as 60 years ago. Your suggestion totally makes sense and many brewers certainly do approach this topic from the perspective you describe.

A quick review of the water from three major brewing centers that are often referenced in brewing texts (see Table 1 that follows), Burton, Munich, and Pilsen, does provide a good framework for the practical brewer. Without diving down the rabbit hole of water chemistry and the interpretation of water analyses, there are some clear differences that can be seen among these water profiles.

The first major difference is that Munich has a higher residual alkalinity (RA) than Burton or Pilsen. Table 1 expresses RA in °dH (degrees of German hardness); the key thing to know is that water with RA = 10 °dH will increase mash pH by ~0.3 pH units compared to using water with RA = 0 °dH, and water with RA = -10 °dH will decrease mash pH by ~0.3 pH units. RA is a value that considers how calcium and magnesium ions react with malt’s phosphates to lower mash pH as well as how bicarbonate/carbonate ions absorb hydrogen to raise mash pH. Dr. Paul Kolbach published the concept of RA back in 1953 in his paper “Der Einfluss des Brauwassers auf das pH von Würze und Bier” (The Effect of Brewing Waters on the pH of Wort and Beer). Kolbach’s research was very practical in that it related to how breweries could use RA to predict mash and wort pH based on brewing water chemistry. This topic is not simple because mash pH is a result of reactions between malt and water, and both water and malt vary. This is one reason water pH has limited practicality to brewers.

Quite simply, breweries historically brewed beers that worked well with local waters and the topic of brewing water followed this tendency.

In order to make sense of this, it is important to know that the pH of a mash made using pale malt and distilled water typically falls somewhere in the pH 5.6–5.8 range. Although a full malt analysis includes wort pH, it is important to note that the Congress Mash used in the ASBC and EBC methods produces a very dilute wort because the total water-to-malt ratio is 8:1 and the wort gravity is usually about 8 °Plato, which translates to about 1.032 specific gravity. This means that the typical 5.8–6.0 pH range for Congress Wort is higher than a typical brewery mash made using the same malt and distilled water as that used in a malt lab. By the way, the term “congress” used in this context means that the mashing method has been standardized by the brewing industry so that results from various labs are comparable.

Back to the typical analysis and the RA values. If water has RA = 0 °dH, the resulting mash pH will have a pH around 5.75 (A.J. deLange, 2004, “Alkalinity, Hardness, Residual Alkalinity and Malt Phosphate: Factors in the Establishment of Mash pH”). pH 5.6 is at the upper end of where most brewers want to be with mash pH and some sort of acidification is required for water with RA = 0 °dH. When the RA of brewing water is greater than 0 °dH, even more acidification is required, and if the water has RA < ~-7 °dH brewers should be cautious about driving the mash pH too low, especially when using darker specialty malts. Mash acidification can be achieved by using darker malts (for example 10% of 50 °L crystal malt reduces mash pH by ~0.3 units, and 10% roasted malt/barley also reduces mash pH by ~0.3 units) using acidulated malt, adding acids to the mash or brewing water, and/or using an acid rest to increase phosphate levels (which in turn react with calcium and magnesium to lower mash pH).

From a practical view, it is easy to see that Munich, traditionally known for its dark lagers, has water in need of some acid to bring the mash pH down from a predictably high level. The dark malts used for the production of dunkles lagers were the source of the acid used by Munich brewers well before our contemporary understanding of water chemistry was known. Although the water values given for Pilsen and Burton have much lower RA values, the predicted mash pH is still on the high side of the typical upper end accepted by most brewers these days. Burton is known for “pale ale,” but higher kilned malts were, and still are, commonly used in the formulation of these beers. And while Pilsen is the home of the golden lager, the traditional triple decoction mash used for the style does include an acid rest and the mash pHs of historical lagers from Pilsen were probably a good fit for the style; otherwise Josef Groll’s revolutionary pale lager that spread across the globe following its 1842 debut may have been a flop. Imagine being at that beer release . . . wow!

Aside from RA, a composite value calculated from carbonate, calcium, and magnesium levels, the balance of the water analysis from these cities does provide further insight for the practical brewer. Burton water contains notably higher levels of magnesium and sulfate, which are flavor active ions. These ions do contribute to the flavor of beers brewed there. Pilsen and Munich have little in the way of flavor active ions — sulfate, magnesium, chloride, and sodium.

From a practical perspective, it seems that the subject of brewing water is often made more confusing and more difficult to approach because of the ways brewing scientists and techno brewers speak about water. I like to simplify confusing subjects for myself so that I can apply them in everyday life. What follows is the way I think about brewing water and how it relates to style.

Mash & Wort pH

Most beer styles turn out well when the mash pH at 68 °F (20 °C) is between 5.4–5.6, and practical dogma tells me that wort flowing into the kettle should not have a pH greater than 6.0 at 68 °F (20 °C). Mash pH is important because enzymes are affected by pH and so is wort filterability during wort collection. If the mash pH is too low, for example when using high levels of dark malts, the easiest way to raise the pH is by adding baking soda (sodium bicarbonate) because it is soluble at mash pH, whereas calcium carbonate is not. If the pH is too high and the beer style being brewed does not (or should not) contain dark malts, add acid to lower the pH; acidulated malt, lactic acid, and phosphoric acid are the easiest ways to decrease mash pH.

Since mash pH is all about enzymatics and wort filterability, it is totally acceptable and functional to adjust mash pH after mashing in because enzymes are not denatured, or otherwise harmed, by slight changes in mash pH. There is nothing magical about nailing mash pH immediately upon the start of the mash! The reason that commercial brewers want to nail pH at this stage of the game is because commercial breweries are businesses, and in the world of production brewing, time is money. Homebrewers operate by a different set of objectives and adding a bit of time at the start of the mash to tweak the pH is probably not going to ruin a brew day. This does not mean that homebrewers cannot learn from the past and adjust water before mashing, but it is far from a requirement.

Another key point here is that lighter styles, like Pilsner, often benefit from wort pH ~5.2 at the beginning of the boil. The lower pH suppresses color pick-up during wort boiling and is believed to make for a softer bitterness. Wort pH can be adjusted once the kettle is full by adding calcium, lactic acid, or phosphoric acid. Although this technique is well known, it seems that many brewers don’t use it. I consider this a brewing trick because it can make a huge difference in the finished beer by doing something relatively simple!

Remember that mash and wort pH are a function of calcium, magnesium, and carbonate from your water, and phosphates, amino acids, and nucleic acids from malts. The most significant information contained in a water analysis, carbonate, calcium, and magnesium, relates to RA and by extension mash and wort pH.

Water Flavor

All the other “stuff” in water pales in comparison to RA. However, the flavor active ions cannot be overlooked. Sulfate enhances hop bitterness and can add a mineral finish to beers at higher concentrations. Magnesium is bitter and metallic; some beers have a distinctive magnesium flavor and adding magnesium sulfate (Epsom salts) is another trick that can be used to tweak a beer. Both chloride and sodium contribute palate fullness and a sort of sweetness to beer at moderate levels. Although the addition of sodium chloride is not something covered in many brewing textbooks, a healthy pinch of kosher salt (not iodized) can definitely enhance the flavor of many styles.

A couple of extremely important things that you will never see in a water analysis are water flavor and chlorine/chloramine levels. Municipal water supplies are chlorinated and the aroma of bleach or chloramine is easy to detect in most tap waters. Carbon filters are great at removing chlorine and are something that all brewers should use to prevent chlorine from tainting beer flavor. The other non-analytical parameter is flavor. Water can taste funky; musty, algal, sulfur, rusty/metallic, and fishy aromas are not uncommon. If you have funky smelling water, consider using another source. After all, beer is 90% water!

Summary

You are probably not thrilled with this answer because I did not give you what you seek. Quite frankly, I think there are way too many tables that attempt to relate brewing science to beer style. In my brewing opinion, the two topics are more often unrelated than they are related. I’ll give you one example that relates to your question. A great brown ale can be made from water that has a RA = 10 or a RA = -3; the difference is that one brew will probably need a bit of bicarbonate to push the pH back up into the 5.4–5.6 range. A great brown ale can also be made by adding a nice dose of salt to the mash, boil, or beer to enhance fullness and sweetness, and a great brown ale can also be made by adding a nice dose of magnesium sulfate to push the beer into a dry, slightly metallic, and more bitter direction. The pH adjustment is brewing science, but the salt additions are part of the brewer’s art and brewing is a blend of art and science.

Response by Ashton Lewis.