Water Treatments

Water is the main ingredient of beer. The many different styles of beer we have today evolved for many different reasons, not the least of which is the chemistry of the local water supply where the beer was created. Historically, brewers no doubt experimented with different ingredients and techniques much as homebrewers do today. They undoubtedly settled on recipes that worked best for what they had readily available . . . including water. Without having a comprehensive knowledge of what was dissolved in their brewing water and its effect on mash pH, expression of hop bitterness, etc. the brewers nevertheless found their way and the rest, as they say, is history.

What’s In the Water?

With the information and technology we have today, we can discern what ions are present in solution in our water and the water of famous brewing regions of the world. If you live in the US and use municipal water, your local water board should send you a summary of what is in your water every year. If you don’t receive this publication, you can request it. Alternately, if you have a private water supply (well, spring, etc.), you should have it analyzed by a private or state-run lab that does such work.

Results shown on water analysis reports are typically expressed in milligrams per liter (mg/L) or parts per million (ppm). In the range of concentrations we are concerned with, you can use these interchangeably. Once you have an analysis of your brewing water, you can compare it to the analysis of the water from brewing centers from around the world and see which beer style fits your local water best. Before we dive into that, though, here’s a quick refresher on the basics of water chemistry.

Water is a molecule composed of a central oxygen atom with two smaller hydrogen atoms attached. A space-filling model of water looks a bit like Mickey Mouse, with the oxygen being his head and the two hydrogens his ears.

Many different types of minerals dissolve in water. When they do, some dissociate (break apart) into their component ions. For example, sodium chloride (NaCl) dissolved in water would dissociate into two ions, Na+ and Cl-. An ion is simply an atom or molecule that has a different number of electrons than protons. This difference results in either a net positive charge (cation) or a net negative charge (anion). These ions float around in solution in water and are available to react with other ions and affect everything from mash pH to the flocculation of yeast.

What if your water is best suited for a Pilsner and you want to brew an Irish stout? Various salts may be added to adjust your water chemistry to suit a particular style of beer. But first let’s look at some important ions in brewing water, how they affect beer flavor, and how their concentrations relative to each other can create flavor synergies.

Basic Brewing Chemistry

Pure water — for example, distilled water or water purified by reverse osmosis (RO) — without any mineral ions in solution, is not used by commercial brewers. It is the dissolved ions in water that are important for mash chemistry, expression of various flavors (sweet, sour, salty and bitter in particular) and yeast nutrition. Therefore it is not a good idea to brew all-grain beer with distilled or reverse osmosis water. (See the table at the top of this page for some general guidelines of desired concentrations of each important ion in brewing water).

Water with high levels of minerals dissolved in it, especially calcium and magnesium, is called hard water. Water with few dissolved minerals is called soft water. For brewers, it is more important to know the concentrations of key minerals that are dissolved in the brewing liquor than whether their water is hard or soft.

Water with very low levels of carbonates (i.e. Pilsen, Czech Republic) will allow mash pH to come into proper range (5.2–5.6) with only pale malt (especially if a little calcium is present). If the carbonate levels are higher, more acidic malt is necessary to properly lower the pH. For example, hard water dominated by carbonates like Dublin, Ireland, with its high level of carbonates, is well suited to brewing stouts. Carbonates and bicarbonates can be precipitated as calcium carbonate (CaCO3) by boiling water in an open kettle for at least 15 minutes where it can pick up oxygen to react with and drop out of solution.

This process will typically reduce carbonates and/or bicarbonates below 150 ppm. Carbonates can also be reduced by neutralizing them with acid. Food-grade phosphoric acid is a popular choice for this in breweries.

Calcium ions (Ca2+) in water react with phosphates in malt, releasing acid. Thus, its presence in mash water lowers the pH of the mash. Calcium is not a significant yeast nutrient, but does facilitate yeast flocculation and subsequent precipitation. Calcium also stabilizes alpha amylase and increases its tolerance to the heat of mashing.

Magnesium (Mg2+) is important for enzyme activity in the mash and for yeast nutrition. Like calcium, magnesium ions drive down the pH of a mash, but to a much lesser extent than calcium. Magnesium enhances beer flavor up to a point, then lends a dry, bitter metallic flavor to beer.

Sodium (Na+) has different effects at different concentrations. At low levels, sodium contributes sweetness, probably by balancing bitterness, and adds some palate fullness, which may be appropriate in certain styles of beer. At higher levels, sodium can contribute to salty flavor.

Sulfate (SO42-) has a very high solubility in water and waters high in sulfate are known as “gypseous” waters. Sulfate ions bring out the hop character in a beer.

Chloride ions (Cl-) give a full, sweet flavor to beer, but they are not a significant player in mash chemistry or yeast nutrition. Many brewers use calcium chloride instead of calcium sulfate because chloride has a flavor affect that many brewers like.

Chlorine (Cl2) is often included in municipal water supplies as hypochlorous acid (HOCl) or chloramine (NH2Cl) to serve as a disinfectant. If either of these compounds remains in brewing water they can lend a harsh, medicinal flavor to beer.

Hypochlorous acid can be removed by boiling brewing water in an open pot for at least 15 minutes prior to using the water in the mash or boil. Remove chloramines from water by adding a crushed Campden tablet to 20 gallons (76 L) of brewing water and letting the water sit uncovered overnight to allow the resulting chlorine gas to dissipate.

Of course, the simplest way to lower an ion in your water is to substitute a portion of your tap water with distilled or reverse osmosis (RO) water that is essentially free of mineral ions. For example; to reduce the concentration of the ions in your tap water by half, use half tap water and half distilled or RO water to make up the total volume of water for the batch of homebrew.

The Short Course on Water Treatment

The details of water chemistry can be complex and many brewers may simply wish to know if they can use their water as is, or learn a simple treatment plan to deal with their water.

Two things all brewing waters require is that they taste good and they be free of chlorine compounds. (See the section earlier for how to treat for these chlorine compounds.)

If you are an extract brewer, the requirements your water must meet are broader than if you are an all-grain brewer. This is because you do not have to worry about mashing your grains. This has been done for you at the malt extract plant. Malt extract is condensed wort, and all (or most) of the dissolved solids present when the grains were mashed are contained in the extract, including mineral ions. When brewing with malt extract, you simply reconstitute your wort from this concentrate. If you use distilled water, or very soft tap water, your reconstituted wort should contain all the minerals required for brewing. If your water is hard, you will be adding minerals to your wort beyond what is required. In small amounts this will likely have no discernible effect. If your water is very hard, especially if it is rich in carbonates, you may want to consider blending it with distilled or RO water to make your brewing water. You do not need to add salts to your brewing water to try to emulate the water of different brewing cities (such as Burton). Unless you know the minerals that are already in your malt extract, you are blindly piling on more minerals. For hoppy beers, you may wish to accentuate the hop profile by adding a little gypsum. Likewise, for malty beers, a little calcium chloride may make for a smoother beer. In either case, don’t overdo the addition. Use a maximum of 2 teaspoons per 5 gallons (19 L) of these salts.

All-grain brewing additionally requires that the water chemistry yields a suitable mash pH. A simplified version of how to obtain this can be had by remembering a few key things. Calcium ions (and to a lesser extent, magnesium ions), dark malts and acids will lower mash pH. Carbonates neutralize acids and decrease the amount that mash pH is lowered by these things.

Calcium has other beneficial actions in brewing, such as stabilizing alpha amylase in the mash. Thus, unless stylistically required to have less, it’s best to have at least 50 ppm calcium in your wort. For pale beers, the amount of carbonates should be minimized, at least under 50 ppm. For dark beers, carbonate can be a good thing and for stouts, your water may require up to 250 ppm carbonates.

Manipulating just the calcium and carbonate levels is the simplest way for an all-grain brewer to treat their water. To reduce carbonates, if needed, you can blend your tap water with distilled or RO water, or add acid. If you need to increase it, you can add calcium carbonate (chalk) or sodium bicarbonate (baking soda).

Once your carbonate levels are adjusted, you can add calcium — if needed — as either calcium sulfate (usually in the form of gypsum) or calcium chloride (CaCl2). Simple water chemistry calculators are available online that will do all the math for you. These include Greg Noonan’s “Water Witch,” available for download at

Whether an all-grain or extract brewer, always taste your brewing water after you have treated it, and don’t proceed if you detect off flavors or aromas. If you do taste something off, double check that you used the correct mineral salts. Don’t taste your water for several hours after adding Campden tablets.

Creating Chemistry

Another approach to dealing with brewing water chemistry is to start from scratch with distilled or reverse osmosis (RO) water and add salts to make the water what you wish it to be. This method may be preferred if you are attempting to brew a beer with a water profile at an extreme end of the brewing spectrum. For example, say you wanted to reproduce the water profile of Dublin, Ireland in order to brew a traditional Irish stout. How could this be done at your homebrewery? Beginning with distilled or RO water, you would need to add some of the major brewing ions (Ca2+, HCO3-, Na+, SO42-, Mg2+, Cl-) to approximate the water profile of Dublin. Charts detailing specific information about the brewing water of famous brewing regions are readily available online or in most brewing texts.

Adjusting or creating a brewing water profile to suit the production of a particular style of beer does not require a degree in chemistry, just a solid understanding of what you need. If you get a handle on the concentrations of the major brewing ions in your water, and compare it to your target water, you can approach your homebrewing water treatment one of two ways — either by altering your tap water to approximate your target water or by starting from scratch with distilled or RO water and adding some commonly available salts.

Reading a Water Report (By Betsy Parks)

Brewing water can be confusing, especially to a new homebrewer who is starting to brew all-grain batches. All you need to know in the beginning, however, is if six certain ions in your water are in the proper range, which you can easily find out from reading a water report.

If you live in a place that has municipal water, you can request a water report from your department of public works. If you are using spring, well, or some other source of tap water you won’t have a public water report, but you can have it similarly tested by a private lab for its content.

Water reports intended for the general public are typically expressed in parts per million (ppm), which is defined as one milligram of the substance per liter (1 mg/L).

The ions

The six important ions in water that you need to know about for brewing are: calcium, magnesium, bicarbonate (or total alkalinity as CaCO3), sodium, chloride, and sulfate.

  • Calcium should be in the range of 50–150 parts per million (ppm). Calcium is an ion that makes water “hard,” and it is important for many yeast, enzyme and protein reactions. Hardness is a measure of the calcium and magnesium content in water. When there is an equal amount of calcium and bicarbonate present, it is known as “temporary hardness,” which can be reduced by boiling. Permanent hardness is measured by the amount of calcium that can’t be removed by boiling. Water hardness is either good or bad, depending on what style of beer you want to brew. For example, temporary hardness is good for dark beers and permanent hardness is good for brewing pale ales. Research the style of beer that you want to homebrew to figure out if the hardness of your brewing water is appropriate for what you want to brew.
  • Magnesium should be in the range of 0–30 ppm. It also contributes to water hardness and is a yeast nutrient. Magnesium is best kept at small amounts because it can contribute off/bitter/metallic flavors to the beer. Magnesium can also give food and beverages a laxative effect, which is another reason to limit this ion in brewing water.
  • Bicarbonate should be 0–250 ppm – or if your report reads as “total alkalinity” it should be in the 0–200 ppm range. More specifically (according to John Palmer’s How To Brew), bicarbonate should be 0–50 ppm for pale, base-malt only beers. 50–150 ppm for amber colored, toasted malt beers and 150–250 ppm for dark, roasted malt beers (these levels assume calcium in the range of 50–100 ppm to balance the alkalinity of the bicarbonate). Bicarbonate affects the pH of your water. A high pH in the mash can cause poor extraction rates, darken the wort, and leach more tannins into your mash. (For more information about pH in brewing, visit
  • Sodium should be between 0 and 150 ppm. Sodium in moderate levels can accentuate malt flavor.
  • Chloride can be anywhere between 0 and 250 ppm. Chloride is similar to sodium in that it can accentuate malt flavor if it is in a moderate range. If there is too much chloride, however, the beer can suffer from off flavors.
  • Sulfate should be around 0 to 150 ppm. Sulfate can accentuate hop bitterness in moderation, but too much can make the bitterness seem harsh.


Issue: Special Issue: Guide to All-Grain Brewing