Brewing Water Treatment in 600 Words

It seems that over the last few years many more home brewers have taken an interest in understanding and modifying their brewing water. And there are good reasons to do so. Depending on the beer that is brewed and the water quality, modifying the brewing water can take a beer from great to excellent. The intent of this post is not to go into the details of water and mash chemistry but to provide an overview of what’s important and paint a high level picture of water treatment for brewing. For those counting, the first paragraph doesn’t count towards the 600 words.

When it comes to brewing water treatment there are 3 goals we brewers are trying to achieve:

• eliminate off-flavor causing water compounds: this is largely the removal of chlorine
• provide a water ion profile that supports the desired flavor of the beer
• provide a water and grist composition that settles at a desirable mash pH

What’s daunting for many brewers is not so much the underlying chemistry, which is easily handled by a brewing water calculator, but the many parameters that can be adjusted.

Chlorine, found in water as free chlorine or chloramine, needs to be removed from brewing water since it forms nasty chlorophenols in beer. Most brewers accomplish this through carbon filtration or Campden tablets (sodium or potassium metabisulfite). Another undesirable water compound is iron. The water’s iron level should be below 0.3 ppm to avoid a metallic taste.

Brewers care about 6 primary water ions that are able to affect the flavor of the beer. The electric charge of the cations (Ca²⁺, Mg²⁺, Na⁺) needs to match the electric charge from the anions (Cl^–, SO₄^2-, HCO₃^–) which is why one cannot be added without the other. Here is a quick summary of what these ions do for the flavor or brewing process:

Calcium (Ca²⁺) is beneficial for the brewing process as it helps with yeast flocculation. It’s also fairly flavor neutral and a recommended minimum is 40 mg/l. The most common means of increasing calcium in water are gypsum and calcium chloride which also adds sulfate and chloride, respectively.

Magnesium (Mg²⁺) from water is not needed since malt provides lots of magnesium to the wort. Excess magnesium can cause a bitter taste. Should be kept below 50 mg/l.

Sodium (Na+) can lead to a salty taste and should be kept below 100 mg/l. Brewers don’t usually add sodium except when baking soda is used to add bicarbonate.

Chloride (Cl^–) creates a softer beer flavor and is desired in malt forward beers.

Sulfate (SO₄^2-) enhances hop bitterness and dries out the beer’s finish. It is desirable in hoppy ales and some brewers even go as high as 700 mg/l. Most hoppy ales should be fine with sulfate levels between 100 and 300 mg/l

Bicarbonate (HCO₃^–) does not affect the taste directly but can have an indirect effect through its ability to raise mash pH out of its desired range.

Mash pH is the result of the balance between pH active water ions, grist and any acid or salt additions that are made. In most cases we are looking for a mash pH in the 5.3 – 5.6 range. These numbers are for a cooled (25 C/ 77 F ) mash sample. Dark malts and acids are the primary drivers of lower mash pH while water alkalinity raises mash pH. Calcium and to a lesser extent Magnesium also lower mash pH but not enough that mash pH control should be done through adjusting calcium or Magnesium levels. In most cases mash pH adjustment requires the addition of acids (lactic or phosphoric are popular choices) to neutralize water alkalinity. Lighter beers may even need more acid to go beyond neutralizing the water alkalinity in order to get mash pH into the desirable range of 5.3-5.6.

To get started you need to find or get a water report for your brewing water, enter the water ion levels and grist information into the Brewing Water and Mash Chemistry calculator and see where you land. From there you can play with salt and acid additions. Target water profiles designed for various beer styles can guide you in your water adjustments.

Image of common brewing salts:

Notably, canning salt, and chalk are not pictured here.

Post by Kaiser