As the main ingredient in all beers, it’s surprising how frequently the importance of brewing water is overlooked. While important, it’s understandable that many homebrewers don’t meddle with water treatments; the fact is it can be extremely daunting. Entire tomes detail the chemistry, and geographical relevance water has played on beer over the years, though these can be difficult to approach for the novice.
In the first part of our brewing water guide, we took a look at what’s in your water and how it can affect your beer. In this second part, we’ll examine how you can treat your water in order to remove off-flavours, enhance hop and malt flavours and characteristics, and improve processes from the mash to fermentation.
Treating Tap Water to Prevent Off-Flavours
Most tap water that is good enough to drink is good enough to brew with straight out of the tap. If your water is treated with chlorine however, you may need to take steps to strip it out, as chlorine can cause medicinal off-flavours in beer. Chlorine alone is not too big an issue, as it will generally dissipate during the boil.
The main problem is chloramine, which is far more persistent and is used in some areas to keep the water bacteria free. Chloramine levels can be greatly reduced by using a carbon filter for your brewing water, however, there’s a quicker, easier and much cheaper method.
Campden tablets (potassium metabisulfite or sodium metabisulphite) are readily available at homebrew stores. The active ingredient is sulphur dioxide, which reacts with the chlorine and chloramines and effectively strips them out of solution. A single tablet will treat up to 75 litres of water, so for most homebrewers, half or even a quarter of a tablet, dissolved into your brewing water a couple of minutes before use will do the trick.
The Most Common Brewing Water Treatments
Different beer styles require different brewing water in order to get the most out of the ingredients. In the first part of this guide, we saw that hoppier beers benefit from higher levels of sulphates, while more malt forward beers are best brewed with chlorides or a touch of sodium. Below you’ll find the most common compounds (salts) used in brewing water treatment.
Calcium Sulphate (CaSO4)
More commonly known as gypsum, calcium sulphate increases water hardness, reduces mash pH, and enhances hop bitterness and dryness. It should be used mainly for flavour rather than to reduce mash pH too much, as too much gypsum will dry out a beer and cause astringency, particularly in less hop forward beers.
Sodium Bicarbonate (NaHCO3)
More commonly known as baking soda, it’s generally used to raise the alkalinity of a more acidic mash, typically those using darker malts such as stouts and porters. Dark malt adds acidity to the mash and it’s good to balance it if your water leans towards a more acidic pH. Too much baking soda will cause salty flavours in your beer, so be wary of using too much.
Calcium Chloride (CaCl2)
This can also be used to reduce mash pH and ensure a nice dry finish. It aids various brewing processes, from improving enzyme activity in the mash, encouraging protein coagulation and trub settlement in the boil and improving yeast vitality and flocculation during fermentation. Care should be taken not to add too much, as this can lead to an unpleasant dryness.
Magnesium Sulphate (MgSO4)
Known as Epsom salts, they’re most commonly used to soak your feet in after a long day brewing. However, small amounts can round of the malt character and enhance hop bite. Care should be taken not to add too much as it can cause a bitter, harsh off-flavour.
Keeping it Simple
With an idea of what you can use to treat your water, you may be pondering the best way you should go about it. Sadly, there isn’t a one size fits all solution, as the brewing water you use won’t have the same chemical makeup as other brewers’ water. You can begin by following basic guidelines such as add a few grams of gypsum in the mash for hoppy ales, or a pinch of baking soda to stouts. Initially this may work well for you — experimentation is key.
If you want more control however, it’s essential you know what’s in your water by obtaining a water report. In this way, you can pull up water profiles for the style of beer you wish to make, and make additions to match. If you find certain ion levels too high for your desired style or just in general, you can dilute it down using deionized water; a common practice when brewing pilsners.
For full control, you can brew with deionized water, or RO (reverse osmosis) water, rather than tap water. These offer a blank canvas, to which you can add the salts you need in order to brew pretty much any style accurately. Brewing water calculators can make it easy to know exactly how many grams of each compound you’ll need to add in order to reach the desired levels.
Most brewing water treatments are added to the mash, generally with the malt. However, you may wish to add some during the boil as well to encourage protein coagulation. Some brewers also treat their sparge water, though this is a topic for another day!
Mash pH in a Nutshell
One final area that’s worth mentioning when discussing brewing water chemistry is the mash pH. We won’t delve too deeply into this subject, but basically it’s important to keep your mash pH within the 5.3–5.6 range. This is the ideal environment for the enzymes to do their thing, ensuring higher efficiency. You’ll need a pH tester to be sure of your mash pH.
The pH of your mash is determined not only by the brewing water profile, but also the grains that go into your mash, as well as any other additions. Darker malts will increase the acidity of your mash, and should typically be balanced out with alkalis such as Sodium Bicarbonate.
Generally however, and especially in more pale beers, you’ll find you’re more likely to need to lower the mash pH rather than raise it. This can be done by adding lactic or phosphoric acid until you fall into the correct range.
While there’s a lot more to learn regarding brewing water chemistry and treatments, this basic guide will set you on the right path. As with all things, it’s best to master the basics first before getting bogged down in the really complicated science.