Brewing Water

The mineral content of brewing water has long been recognized as making an important contribution to the flavor of beer. This is especially important since water composes more than 90% of the beer. Brewers interested in brewing a particular beer style first need to evaluate whether or not the their water is suitable by comparing it to the water analyses of a flagship brewery or to the water used to produce the beer style in the regions of its origin. For example, the water of Dublin for stouts, the water of Burton-on-Trent for dry, hoppy pale ales and so on.

Historically, different regions have become famous for their classic beer styles as defined by the waters available for brewing. For example, the famous brewing waters from the deep wells at Burton-on-Trent are known for their excellent qualities in brewing full-flavored pale ales. Burton water is high in permanent hardness because of the high calcium and sulfate content, but it also has a lot of temporary hardness from a high level of bicarbonate. Munich water is poor in sulfates and chloride but contains carbonates, which are not very desirable for pale beers but ideal for producing darker, mellower lagers.

pH, Alkalinity, and Water Hardness in Brewing Water

pH

When water molecules are ionized, they produce hydrogen (H+) and hydroxyl (OH-) ions, which carry an electrical charge. These ions in the water determine its fundamental character-whether it is acid (excess H+) or alkaline (excess OH-). The term "pH" refers to the hydrogen cation (H+) concentration in water and is defined as the logarithm of the reciprocal of the hydrogen-ion concentration.

Alkalinity

Alkalinity is a measure of the buffering capacity of the bicarbonate ions and, to some extent, the carbonate and hydroxide ions of water. These three ions all react with hydrogen ions to reduce acidity and raise pH. Alkalinity is normally given in mg/l as calcium carbonate (CaCO3) for all three ions.

• Residual Alkalinity

The result of the competition between the pH increasing and lowering properties of water is determined by the residual alkalinity (RA). The residual alkalinity is the difference between carbonate (carbonate + bicarbonate) hardness and non-carbonate hardness.

Water Hardness

Total water hardness is the measure of the bicarbonate, calcium, and magnesium ions present in the water. Total hardness is expressed as mg/l of calcium carbonate (CaCO3), which determines the degree of softness or hardness. Generally, a measurement of fewer than 50 mg/l is considered very soft water, 50 to 100 mg/l is considered soft water, 100 to 200 mg/l is considered medium-soft water, 200 to 400 mg/l is considered moderately hard water, 400 to 600 mg/l is considered hard water, and greater than 600 mg/l is considered very hard water.

• Temporary Hardness

In the United States, temporary hardness results from calcium, magnesium, and sodium salts of carbonates and bicarbonates in the water. Most of the hardness is attributed to calcium bicarbonate.

• Permanent Hardness

Permanent hardness is that portion of total hardness remaining after the water has been boiled. Permanent hardness results from calcium and magnesium salts of sulfates and chlorides remaining in the water.