Americus city water is good for brewing beer. Our water could be summarized as being low in minerals and slightly alkaline. The testing results show low calcium (12 to 15 ppm), low magnesium (<1 ppm), low sulfate (<12 ppm), and moderate alkalinity (40 to 50 ppm). The pH is 7.4 to 7.6. One report also shows high silica, which is "relatively inert, but can create colloidal haze" (Mosher, 1995, p. 115). The details are available in the following documents.
The only way to definitely know the chemical composition of your brewing water is to have it tested. This is especially true if you live outside the city limits and have your own water well. The agricultural extension agents at the Sumter Ag Center (phone: 924-4476) can perform water tests. Their office is located at 331 Highway 19 South, which is about 1/2 mile south of the intersection between Highway 19 and Highway 280. The W2 test gives the most complete information. This test requires at least one pint of tap water and costs about $50.
The city tap water is treated with chlorine (about 1 ppm) to kill microbes. This chlorine can be removed by filtration with carbon filters. Other treatment approaches include campden tablets and allowing the water to stand overnight. My favorite approach is to use filtration. This technique can easily create as much chlorine-free water as you need at a low cost.
Americus city water has concentrations of calcium and sulfate that are below the recommended minimum concentrations for most beer styles (recommended calcium - 50 ppm; sulfate - 50 ppm; Stika, 2009). Modest amounts of these minerals should be added to ensure good yeast health and flocculation. The necessary mineral additions depend upon the beer style and mash pH. Adding one teaspoon of either calcium chloride or calcium sulfate (gypsum) to the mash will help raise the calcium concentration to recommended levels. Calcium chloride is generally preferred for malty beers whereas calcium sulfate is preferred for hoppy beer styles.
The magnesium levels in our city water is below the recommended five to 10 ppm (Stika, 2009; Palmer and Kaminski, 2013). Fortunately, there is no need to adjust for low magnesium. The mash provides all the magnesium that is needed for good yeast health (Palmer and Kaminski, 2013, p. 46).
Americus water is moderately alkaline, with a pH of about 7.5. Palmer's nomograph (see below) for mash pH suggests that base malt mashed in our water would yield a pH of 5.75, which is a bit higher than the desired mash pH target of 5.4 to 5.6. Americus water is ideally suited for amber-colored beers.
All-grain beers with medium crystal malts or darker malts should not require any adjustments for mash pH. Pale beer styles, on the other hand, may require some extra attention to hit the proper mash pH. There are several possible strategies. One strategy would be to dilute the tap water with distilled water to reduce the alkalinity of our tap water. A second strategy for reducing pH would be to include a small amount of acidulated malt (about four to six ounces) in the mash. A third strategy would be to add a small amount of phosphoric acid (about 1 teaspoon) or similar acid directly to the mash. Of course, you can always adopt the "relax, don't worry" strategy: Pale beers usually turn out fine without much fiddling.
Our slightly alkaline water may also pose some concerns for continuous sparging. My experience with continuous sparging is that untreated tap water will result in astringency because the sparge water is too alkaline. This problem can be fixed by adding three teaspoons of phosphoric acid (10% solution) to six gallons of sparge water. The phosphoric acid reduces the pH to about 5.8 to 6.0.
The Merry Cuss brewers should be glad because our water is pretty easy to brew with. All-grain beers usually turn out just fine without much fiddling. I hope you can use this information to fine tune your brews.
By Gary Fisk (February 14, 2017)
I thank Mary Ann Rouse, Tom Weiland, David Minich, and Tzvetelin Iordanov for helping me with this project.
Mosher, R. (1995). The Brewer's Companion: A Source Book For the Small Scale Brewer. Alephenalia Publications, Seattle, WA
Palmer, J.J. (1999). How To Brew. 1st edition. Brewer's Publications, Boulder, CO
Palmer, J.J., and Kaminski, C. (2013). Water: A Comprehensive Guide for Brewers. Brewer's Publications, Boulder, CO.
Stika, J. (2009). Water profiles: Create your own chemistry. Brew Your Own, 15(6), 54-57.
Weiland, T. (2008, personal communication)