Water Chemistry Primer for Brewers

Excerpt from BreWater 3.0 Help file. BreWater is a freeware water treatment calculator for Windows.

Water Treatment is a topic many (most?) brewers overlook; either (1) "My beer's fine with tap water" or (2) "I ain't no chemist!". Both statements may be true but (1) your beer just might be better with some water treatment and (2) the fundamentals of water chemistry are not hard to grasp. I hope this primer will help you understand your brewing situation just a bit better.

By far water treatment is more important when mashing than it is for extract brewers, although extract brewers may need to make adjustments to very "bad" water, or even "build" water from scratch, to make a better brew.

"Building" water simply refers to adding controlled amounts of certain salts and bases (hereafter referred to collectivley as "salts") to water of known "ionic profile", to yield water with a new profile with the desired characteristics. Typically one would obtain one of the many published profiles for "classic" brewing cities and try to emulate that water. Distilled or other ion-free water is normally the starting water of choice, unless one has an accurate and reliable analysis of his/her tap water to use (they're free for the asking from your local utility; how accurate and reliable they are is another thing!).

Unfortunately, it is usually difficult or impossible to exactly match (or even to closely approximate in some cases) a given target profile without resorting to elaborate techniques and additives to which most of us have no access. Even then we can normally only hope for a reasonable approximation. But we can also come pretty close in many cases with the addition of a few readily-available salts to either ion-free water (distilled, RO, deionized), or tap water (if we know the tap water's "profile"). As we will see, this is usually more than adequate for accomplishing our goals.

Most published profiles concentrate on the levels of calcium (Ca), sulphate (SO4), magnesium (Mg), sodium (Na), chloride (Cl), and carbonates (CO3 or HCO3). Other water constituents have only secondary effects on the beer (if any), and in the amounts found in regulated municipal supplies, they can be ignored. (One exception might be iron, which will ruin your beer if it's too strong. If you can taste it in the tap water, it's too high; use different water. This is normally a problem only in well water or in homes with old rusty pipes!) We can increase each of these ionic components by adding measured amounts of gypsum, epsom salt, non-iodized table salt, baking soda, chalk, and calcium chloride dihydrate. These are readily-available either in grocery or drug stores, or from homebrew supply houses. Calcium chloride is one you might have to search a bit for, but it's out there.

Let's assume you have a desired water profile in front of you. The question is: how much of these salts do I add to get the ion levels I want? Adding one gram of the salts shown to one gallon of ion-free water yields the following increase in the ppm (or mg/l) concentration of their constituent ions (contributions of hardness and alkalinity are also shown):

Since you cannot add just one ion without adding another, this is an iterative process that may or may not ever result in a close match.

As we will see, of these ions, only calcium and carbonates play a significant role in mashing. (Alkalinity arises from carbonate and can be qualitatively treated as equivalent in effect). However, the other ions are involved in flavor and other beer characteristics and need to be considered as well.

Highlights of Mash Chemistry

The mash contains a number of chemicals based on phosphorous, which are weak acidic buffers. It's these phosphates that cause the pH of a mash to drop into the "high-five's" when neutral water (pH = 7) is used. But the mash enzymes work best at lower pH's around 5.2. So we often must aid the acidification of the mash. Calcium reacts with the phosphates to form insoluble compounds which precipitate out of the mash. In addition, hydrogen ions are released in this process. Hydrogen ions (H+) are the defining constituent of acids, so we get acidification not only from removal of the buffering ("stabilizing") phosphates, but by the addition of H+ ions.

So calcium is crucial to proper mash acidification. This is why it's often advised to add gypsum to your mash water. However, this advice is often incorrectly interpreted to mean that gypsum is an acid. This is definitely not the case! Adding gypsum to sparge water is not a method of lowering the pH!! It's the calcium in gypsum, reacting with the phosphates in the mash, that lowers the pH.

Carbonates (or, more accurately, the carbonic species) have the opposite effect; they are alkaline which means they will counteract acids and raise the pH. To an extent, in small quantities, they help prevent overacidification of the mash (they too have "buffering" capacity), and therefore some carbonate level is probably helpful, but in general we want to eliminate as much as possible. Carbonates will react with calcium to form insoluble precipitates, so they can strip out the calcium we need to set the pH. Grain bills with lots of dark roasted grains are naturally more acidic than pale mashes and can therefore tolerate greater carbonate levels. This is why brewing darker beers successfully is often easier than is brewing lighter beers with alkaline water such as is found in London. Carbonates can be removed by boiling the water and allowing any calcium to react and form precipitates; decarbonated water is decanted off the precipitate once cooled. This requires that there is already some calcium in the water being boiled, however, and in any case not all the carbonates will be removed. When "building" brewing water using salt additions to match a certain target ion profile, consider the target profile's carbonate numbers a "maximum" target and don't worry if you come up "low" on this ion.

"Hardness" and "Alkalinity" are of course not ions, but are secondary measures of water quality having to do with the presence of certain ions. Hardness comes from calcium and magnesium content, and alkalinity comes from the carbonic species (carbonic acid or dissolved CO2, carbonate, and bicarbonate). Alkalinity is related to pH but is not a direct measure of it. However, it is a direct measure of the "buffering" capacity of the solution, or its "resistance" to attempts to change its pH. In other words, the higher the alkalinity, the more acid would be required to begin to change the pH. Two solutions with identical pH's but differing alkalinities will require different levels of acidification to lower the pH to a given number. This is why an alkalinity figure is more useful than a "carbonate" figure in evaluating water chemistry for brewing. Both Hardness and Alkalinity are often quoted to be "as CaCO3", which simply relates it to the alkalinity contributed by a certain amount of chalk (CaCO3).

The other ions dealt with in simple "water construction" have no (or only minor) roles in the mash chemistry, but are important in the flavor of the finished product. General effects of the ions on beer character:

Calcium (Ca): Aids in extraction of fine bittering principles from hops. Enhances protein coagulation (hot & cold break). Beneficial to yeast. Aids shelf life. Helps establish an optimum mash pH. I've also found that ample calcium helps build body; low-calcium water (<40 ppm) can produce thin beer. 50 - 200 ppm is typical.

Sulphate (SO4): Lends a dry, sometimes "sharp" character; accentuates hops. Normally best below ~50 ppm but can go as high as 700 ppm or more in Burton-style ales.

Magnesium (Mg): Beneficial to yeast in small amounts, but is objectionable in high concentrations. Best kept to 10 to 30 ppm.

Sodium (Na): Adds a "fullness" and "sweetness" to beer in reasonable concentrations. Keep under 100 ppm (usually under 50), especially in the presence of sulphate.

Chloride (Cl): Adds a "fullness" and accentuates bitterness. Keep under 100 ppm (usually under 50), especially in the presence of sulphate.

Carbonates (CO3:) Harshens hop bitterness; reddens beer; hinders protein coagulation. Best kept below 50 ppm; high levels of calcium in the mash can offset it (due to phospahte acidification reactions), as can use of dark roasted grains.

"If I don't mash, I don't need to worry about water. Right?"

Well, perhaps not as much, but yes, there are still things to take into consideration.

As described in the Water Chemistry Primer, in addition to the chemistry of mashing, we must consider the impact of the ions on flavor and character. But with extract, we're at a disadvantage, since someone (the extract manufacturer) has already done the mashing and didn't share the water recipe with us! What's in the extract? Hard to tell, but according to one major extract manufacturer, condensate (steam) from earlier mashes is collected and reused. This is essentially deionized distilled water! Some local water is used to make up the difference, perhaps 30% of the mash water. This approach to extract manufacture avoids waste, since perhaps 70% of the water used is recycled into the next batch (having been removed from the wort, leaving behind extract), and my suspicion is that many if not most manufacturers will use condensate for a large portion of their water.

But even with 30% local water, ion content can be significant, especially if the water is very hard. For example, if an English extract manufacturer uses Burton makeup water with 300 ppm of SO4, the beer you brew from the extract will have about 30% of this or around 90 ppm. This is more than you'd like in many styles. However, if the extract manufacturer uses relatively soft local water, you might expect fairly nominal concentrations in the final beer.

As a starting point for estimating water treatment for extract brewing, try to find a water profile for the area in which the extract is produced. Take about 30% of the values for the ion concentrations as an initial guess, add that to your untreated water ion levels, and work your treatment from there. It will only be a guess, but a somewhat educated one. If you cannot find a profile, consider the approach of using ion-free water for brewing most styles, adding salts only when unusually high levels of ions are called for (IPA's for example), and otherwise assuming that adequate amounts already exist in the extract. And try to use an extract that was made in the region where the style you are brewing comes from. These steps should bring you a lot closer to authenticity.

Remember too that if you are adding a lot of roasted specialty grains (steeping or partial-mashing), your pH is likely to be lower (more acidic) than usual, so you may want to adjust with chalk or baking soda to prevent an overly-sour finished beer. Check that your wort pH is not under 5.0 at the start of the boil.

These recipes are general-purpose "idealized" formulas for creating water from distilled for all-grain brewing. Refer to the above text for ideas for extract brewers.

These recipes are for five gallons of ion-free water; scale up or down as needed. They are definitely "ballpark" profiles and can be adjusted liberally as desired. I'll "leave it as an excercise to the reader" to verify the resulting ppm concentrations using BreWater.

When chalk is called for, you'll have to get it dissolved by bubbling CO2 through the water and acidifying it that way (which works but takes time; allow to sit overnight after adding chalk to allow excess CO2 to escape), by adding to water acidified with brewing acid, or you can stir the proper amount directly into the mash, and let the mash's acidity dissolve the chalk. When sparging, stir the chalk directly into the sparge water so that it's well-suspended, then acidify your sparge water to your favorite pH (5.7 is typical). This should help dissolve the chalk (to incorporate the desired concentration of calcium) while neutralizing the detrimental effects of the alkaline carbonate by lowering the pH. Remember that we're trying to emulate the makeup of the water naturally found in regions where these beers are brewed; whatever the local brewer would do to those "natural waters", we should do too. But also note that if the mash has ample calcium to establish a pH of about 5.2, then adding more carbonate simply to "match" a profile is probably counterproductive, especially if you're going to then acidify to lower the pH! Again, let the pH be your guide to how much chalk or baking soda to add; add a portion of it and continue only as long as your pH is in range.

These recipes are based on published profiles; I make no claims as to their suitability for their styles other than that the recipes should yield the indicated ion concentrations.

Burton Pale Ale -- A toned-down, "idealized" profile. Enough sulphate to bring out the hops without overdoing it. Low alkalinity helps ensure proper mash pH.
1.4 gram baking soda, 1.9 gram calcium chloride, 3.5 grams Epsom salt, 9 grams gypsum. Ca=110, SO4=299, Mg=18, Na=17, Cl=50, carb=53, Hardness=380, Alkalinity=44.

English Ale -- A London well-water profile.
3.7 grams Epsom salt, 2.9 grams baking soda, 2 grams chalk (add to mash), 2 grams canning salt, 0.3 gram gypsum. Ca=46, SO4=85, Mg=19, Na=83, Cl=64, CO3=173, Hardness=195, Alkalinity=197.

Light Lager -- Very small amounts of ions; have some lactic acid on hand to acidify the mash. Might be easier using ion-free water!
0.2 gram Epsom Salt, 0.25 gram chalk, 0.1 grams canning salt, .1 gram gypsum. Ca=6.5, SO4=7.1, Mg=1.0, Na=2.1, Cl=3.2, CO3=7.9, Hardness=21, Alkalinity=13.

Medium Lager -- Malty, amber lagers like Oktoberfest.
0.5 gram Epsom salt, 0.7 gram baking soda, 4 grams chalk (add to mash). Ca=85, SO4=10, Mg=2.6, Na=10, Cl=0, CO3=153, Hardness=222, Alkalinity=233.

Dark Lagers -- Bocks, for example.
2.3 grams Epsom salt, 2.7 grams baking soda, 3.7 grams calcium chloride, 2.2 grams gypsum. Ca=80, SO4=112, Mg=12, Na=39, Cl=94, CO3=102, Hardness=250, Alkalinity=85.