The North State Brewers' Cooperative

Seven types of ions contribute significantly to beer. A thorough description of these ions and their optimum concentrations can be found in Appendix A.

Usefulness

In order to gain a full understanding of the condition of water, it is necessary to obtain a chemical analysis of your drinking water from your local water treatment plant. Here in Ann Arbor, we find that all of the seven significant ions are within their reasonable concentration ranges, except for calcium. Calcium has a concentration of 37 mg/L, but we'd like 50-150 mg/L. In order to increase the concentration of the calcium ion, we need to add 0.25 oz (or 1/2 Tbsp) of Gypsum (CaSO4). This will increase both our calcium concentration by approximately 85 mg/L (leveling off at 122 mg/L) and our sulfate concentration by approximately 207 mg/L (leveling off at 263 mg/L). Thus, both our calcium and sulfate ions will be within their respective acceptable ranges with our addition of Gypsum.

Conclusion

In order to attain usable brewing water, we must check to make sure all of our seven significant ion concentrations are within their respective acceptable ranges. Failure to perform this check could result in bitter or salty off-flavors, a hazy look, poor flavor stability, less than optimum mouthfeel, and darkened color.

Sources

Ray Daniels, Designing Great Beer, copyright 1996 Charlie Papazian, The New Joy of Homebrewing, copyright 1991 Charlie Papazian, The Home Brewer's Companion, copyright 1994 Stephen Snyder, The Brewmaster's Bible, copyright 1997

Appendix A: Significant Ions and their Concentrations

Carbonate (CO3-2 )
Determines temporary or "carbonate" hardness. Carbonate inhibits crucial chemical reactions in the beermaking process as well as secondarily influencing beer characteristics. It is alkaline in nature and neutralizes acids. In doing so, it counteracts the beneficial and necessary effects of calcium and magnesium. Carbonates contribute to an increase in color extraction of specialty grains (undesirable for light-colored beers). Carbonates also contribute a harsh character to the flavor of beer by extracting excessive tannins from grain husks. Since darker beers are inherintly more acidic, relatively high levels of carbonate are fine for these. Levels should generally be no higher than 25-50 mg/L for pale beers, 100-300 mg/L for dark beers.

Bicarbonate (HCO3-)
This anion has twice the buffering capacity of carbonate. But, although bicarbonate is a stronger alkaline, it is less stable and can be removed from water by simply boiling water and aerating.

Chloride (Cl-)
Contributes a fullness to the flavor of beer, accentuating the malty character. Like sodium, contributes to the overall mouthfeel and complexity of the beer. Levels generally should not rise above 150 mg/L.

Sulfate (SO4-2)
Draws increased bitterness from the hop during boiling and contributes a drying bitterness to the beer flavor. Levels generally should not rise above 450 mg/L.

Calcium (Ca+2)
This is perhaps the single most important ion. It reacts with phosphates naturally present in malt to acidify the wort, thus lowering the pH. Calcium helps inhibit color darkening (for light beers), decreases pickup of tannins (i.e. decreases haze and astringent phenolic flavor), and enhances yeast health. Levels should generally be between 50 and 150 mg/L.

Magnesium (Mg+2)
This cation promotes reactions similar to calcium but to a much lesser degree. In limited amounts, it is beneficial to yeast metabolism. In excess, it will contribute a sour-bitter-salty sensation. Levels should generally hover around 20-30 mg/L.

Sodium (Na+)
Accentuates a malty-sweet fullness in beer. In excess, it will contribute a salty character. Contributes body, full mouthfeel, and character. Levels generally should be in the 10-70 mg/L range.