The Oxford Companion to Beer definition of

water

Water can easily be argued to be the most important raw material in brewing, representing as it does 85%–95% of most beers. Breweries are heavy users of water throughout the brewing process, where it is used for mashing, sparging, cleaning, sanitizing, wort chilling, steam generation, and more. Even the more efficient breweries will use 4 to 5 liters (or 1.06 to 1.32 gal) of water to every liter of beer produced with the “world record” in 2011 standing at a bit more than 2 to 1. Although all uses of water are important to the brewery, the water that ends up as part of the beer naturally takes precedence.

Water Sources

Historically, significant breweries have always been built close to suitable supplies of good water. The composition of the local water impacted the beer styles and traditions that arose in many of the classical European beer countries or regions such as Plzn (Pilsen) in the Czech Republic, Burton-on-Trent and London in England, Bavaria in Germany, Dublin in Ireland, Munich in Germany, and Vienna in Austria, etc. Fundamentally, the most significant differences in the composition of water are determined by whether it is from a surface water source (reservoirs, rivers, streams, or lakes) or a ground water source, such as aquifers, wells, or a municipal water supply based on ground water. The basic difference is that surface water is virtually mineral free because it is made up of recent precipitation, whereas ground water can be anything from very soft (low in minerals), as found in Czech Bohemia (Pilsen), to the very mineral-rich water in Burton-on-Trent. See burton-on-trent.

These differences depend on local geology, which determines both the time it takes for precipitation on the surface to drain down to the aquifers (water-bearing geological layers) from where it is drawn and the chemical composition of the geolayers between the surface and the aquifer. These two factors combined determine which minerals the water takes up and in which concentrations during this process.

Water Treatment

Today, most difficulties with local water supplies can be overcome by technological means. With the introduction early in the 20th century of industrial water treatment, the traditional ties between local water composition and beer quality were eliminated to the extent that today any brewery anywhere in the world can, given a suitable water treatment system, create any desired composition of the water used for brewing, sometimes called “brewing liquor.”

Diverse techniques are available for treating brewing water. These vary not only with the desired end quality of the treated water but also with the composition of the untreated water, as well as with the age and technological sophistication of the water treatment systems. Such systems range from simple depth filtration, which uses sand to remove just particulate matter, to reverse osmosis that removes virtually all “foreign” molecules and ions from the water, leaving it almost as pure as distilled water. Which system—or combination of systems—is used at individual breweries will depend on a multitude of factors, of which by far the most important is, of course, the requirements for producing a brewing liquor that is ideal for the quality of the beer styles the brewery chooses to make. This is clearly the case for larger and more modern breweries, whereas smaller and older breweries often have to live with either an archaic or an overly simplistic system or even no water treatment at all.

Water Hardness

The chemistry of the water has a significant impact on the flavor of the beer brewed with it, and one of the most important elements in water chemistry in this respect is its hardness. This is an ancient descriptor of the combined contents of the anions sulfate and bicarbonate and the cations calcium and magnesium. Water containing high concentrations of these minerals is said to be hard water, and conversely water with low mineral content is said to be soft water. Hardness can be divided into permanent hardness (calcium and magnesium sulfate) and temporary hardness (calcium and magnesium bicarbonate). As the name hints, temporary hardness can be removed by boiling the water, causing precipitation of calcium carbonate and leaving the water softer once it cools. This water can then be removed or decanted off the precipitate. Boiling will not remove permanent hardness, however, a term that generally denotes sulfates and chlorides of calcium and magnesium. Despite the name, water containing high permanent hardness can be softened by the use of chemical additives that react with and precipitate the hardening minerals. Softening can also be achieved by the use of devices that replace calcium and magnesium ions with sodium or potassium ions; these devices are common in many people’s home water systems.

Calcium, and to a lesser extent magnesium, lowers the water’s pH by reacting with phosphate and other ions. Bicarbonate raises its pH. The net pH that results from the level of calcium, magnesium, and bicarbonate impacts (among other things) the extractability of various malt and hop components into wort and the quality of perceived bitterness.

The calcium and magnesium that make up the permanent hardness are, however, highly desirable in moderate concentrations.

Water Chemistry and Beer Quality

The ions present in water (and other brewing raw materials) have various impacts:

Calcium (Ca2+): Decreases pH (acidifies) and stabilizes alpha-amylase during mashing. Calcium improves the sedimentation of both trub and yeast after fermentation and precipitates calcium oxalate that might otherwise cause gushing in beer.

Magnesium (Mg2+): Enzyme cofactor. However, too much magnesium can result in an astringent bitterness.

Sodium (Na+):

Affords saltiness. Gives a fuller, rounder, sweeter taste in moderate concentrations.

Potassium (K+): Can give similar flavor effects to sodium. Although small amounts are necessary for healthy yeast, higher concentrations can interfere with enzymatic activity in the mash. Laxative.

Iron (Fe2+): An oxidizing agent; can cause haze in worts and gives a metallic off-flavor to beer.

Zinc (Zn2+): Stimulates yeast by activating alcohol dehydrogenase. Foam enhancer.

Bicarbonate (HCO3): Increases pH. Gives a less fermentable sugar profile from mashes and can produce difficulties in separation of proteins and polyphenol complexes during the cold and hot breaks. This can later cause difficulties in filtration. Causes scaling in brewery vessels and piping.

Sulfate (SO42+): Gives a drier and more pleasantly bitter taste and flavor in moderate to high concentrations. Gives rise to a sulfidic aroma and flavor when reduced by yeast.

Chloride (Cl): Mellows out and increases the fullness of the palate of the beer.

The positive effects, especially in the brewing of many traditional English style ales, of the calcium, sulfate, and chloride ions has given the name to a very specific adjustment of water used for brewing such beers. It is called Burtonization—named after the well water in Burton-on-Trent—and involves an addition of calcium sulfate (gypsum) and calcium chloride to the water. See burtonization.

In many areas of the world, the public water supply is chlorinated and it is essential that such chlorine be removed from the water before it is used for brewing. If it is not, the chlorine will react chemically with diverse organic compounds in the malt, resulting in the formation of organochlorines that have strong, penetrating, unpleasant bandaid like phenolic off-flavors. Dechlorination is most commonly carried out with activated carbon filters that also remove any organohalogens created by the chlorination.

<p>Bibliography</p>

Hough, J, S., D. E. Briggs, R. Stevens, and T. W. Young. Malting and brewing science, 2nd ed. Cambridge, UK: University Press, 1982.

Kunze, Wolfgang. Technology brewing and malting, 3rd international ed. Berlin: VLB Berlin, 2004.

Anders Brinch Kissmeye