An Introduction to Water Chemistry in Brewing
Oct 27, 2015
When I began Home-brewing, I had no idea that one day, six years later, I would be emailing the head of my city's water department to ask how much calcium, bicarbonate, and magnesium was in my drinking water. Water makes up more than 90% of the beer, but it rarely gets any of the press. Hops, malt, and even yeast get more of the attention than water does. The contribution that hops make to a beer is obvious, especially with the popularity of hop-forward American styles. Drink an English porter, Irish stout, or German Vienna Lager, and the flavor that malt adds to a beer becomes obvious. The growing popularity of Belgian-style Farmhouse Saisons shows that we can appreciate the phenol and ester compounds that yeast bring to the party. The common denominator between all these varied styles is water, but what does it do for the beer?
One of the reasons that water isn't talked about very often in the brewing process is because it is very complex, and takes a good understanding of chemistry to master. The brewer, not the drinker, is the main person that really needs to know about the water in their beer. As a craft beer drinker, it's easier to appreciate the other ingredients in the beer, as they have a more obvious impact on the flavor. As a brewer, water is important because lot of the impact that water has is in mash tun, on the chemistry side of things. The water is the stage on which the enzymes and starches in the mash perform, and it sets the scene for the fermentation later on. The primary function of water chemistry in a beer is to get the mash PH at an optimal level for mash enzymes to function. When the mash is between 5.2-5.6 PH, the enzymes can function at their optimum level, and make the best wort possible for the yeast to ferment. The brewer's primary job is to get the residual alkalinity and PH of the water to an optimal level so that the enzymes can do their work.
The secondary function of water in beer is flavor. While water doesn't have an overt flavor of it's own, the minerals and compounds in a water source can accentuate different flavors in a beer, both positively and negatively. For example, many municipal water sources
include Chlorine or Chloramine in their tap water. This provides certain benefits under normal conditions, by providing anti-microbial qualities to keep the water free of bacteria as it travels from the treatment plant to your home. For brewing beer, it is very undesirable. Chlorine and Chloramines react with phenols from the yeast or malt to form Chlorophenols. Chlorophenols taste "medicinal", often compared to acetone or bandaids, not a flavor you desire in beer. On the other hand, some naturally occurring elements in water can enhance desirable flavors in a beer. Sulfates can bring out the hop flavors in a beer, while Sodium and Chloride work better in beers with less hops, bringing out rich and complex malt flavors. These minerals all exist in our drinking water, in differing amounts, based on the source of the water.
Many of the beer styles we know today were developed based on the water that was available in the region where it was brewed. Without the ability to adjust the water chemistry, brewers used trial and error to figure out what styles of beer worked well with the water they had available to them. This is why the Pilsner was brewed in an area with very soft water, high in sulfates that accentuate its bright hoppy flavors and clean finish. English porters and stouts were brewed in Burton on Trent, where there are high levels of sodium and chloride showcase the rich coffee, chocolate, and toffee characteristics of the english black patent malts. Today, brewers, and even home-brewers, have the ability to change the water they brew with to make the best beers possible, no matter what style. Water chemists can help Coors brewers make beer with the famous "Rocky Mountain Water" anywhere in the world. Homebrewers can start with distilled water and recreate the water flowing out of the taps in Munich, Germany. This is just the very surface (pun intended) of water chemistry in beer, but hopefully you have a new appreciation for the seemingly bland, but ever important, life-giving liquid that is H2O. Check back for more information on what water can do for your home-brew, and how to get there. Until then, stay hydrated. Cheers!