Water. It seems simple enough, right? Although seemingly basic, the ingredient that makes up the largest part of beer is far from homogeneous.

Water can significantly influence the taste, aroma and overall quality of the finished beer, while also affecting mouthfeel and hop bitterness.

The first factor concerning water a brewer-in-training needs to consider is pH level. The pH (the acidity or alkalinity) of water can impact enzyme activity during mashing, affecting the conversion of starches into fermentable sugars. 

Most enzymes responsible for this conversion work optimally in a specific pH range — generally between 5.2 and 5.6. 

By measuring and adjusting the pH of the brewing water, a brewer can ensure efficient sugar extraction and have better control over the finished flavour profile. Using pH test paper is a cheap and easy way to do this.

The pH level in strike water or the mash can be adjusted using food-grade lactic acid or acidulated malt. It’s best to start with small additions and add more once your confidence builds.

Dark malts will also acidify the mash, so when brewing with those you need less acid from other sources. 

As a brewer becomes more experienced, they may start to consider the minerals present in water — calcium, magnesium and sulphate play crucial roles in the brewing process. 

Calcium promotes the extraction of flavours from hops and helps with yeast flocculation, contributing to clarity in the final product. 

Magnesium can enhance the perception of malt sweetness. 

The sulphate-to-chloride ratio can influence mouthfeel, emphasising either a crisp and dry or a fuller and rounder texture. 

Understanding the water profile allows for better recipe formulation and replication of specific beer styles. Brewing a hop-forward IPA, for example, may require adjustments to accentuate hop bitterness and aroma, while a malty beer might benefit from water modifications that enhance the richness of the malt character. 

So, how does the brewer make the most of water chemistry in a practical sense?

First, it’s important to know what the water contains from the outset. Different parts of the country have different mineral compositions. Councils have records of the local water supply and should be willing to hand it out. A local brewery may also do the same.

Minerals in water are measured in parts per million and they are adjusted using inexpensive compounds available at good home brew shops.

Calcium sulphate is one that is often used to replicate the mineral-rich water of Burton-on-Trent in England, where the IPA style originated. This “Burtonisation” is used to harden the water and lend to the beer’s hop bitterness. Other products include calcium chloride, calcium carbonate and magnesium sulphate.

The adjustments required to replicate a water profile can be found online and it’s best to use brewing software such as Brewer’s Friend to calculate additions.

Also, chlorine and chloramine, commonly found in tap water, are potential enemies to a homebrewer. These compounds can impart off-flavours, often described as medicinal or band-aid-like. Campden tablets are an easy method  to remove chlorine and chloramine.

Finally, keen homebrewers should look up Greig McGill’s recent articles for the Brew Shop blog (a two-part series titled The Biggest Ingredient), which are fantastic reading. 

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