I know. Water sounds boring. It’s, well… it’s just water, right? But, let’s face it – beer is over 90% water! It’s the main ingredient by volume. So starting with clean, quality water is crucial for a good final product. The profile of the water used affects the pH of the beer, which influences how the flavors of the beer are expressed on the palate. The right minerals can make a beer more flavorful, while the wrong additives can create off flavors.
The water needed for brewing should be free from chlorine and other chemicals, but does need to contain certain minerals. If the water is of a good drinking quality, it’s probably good for brewing – unless it’s distilled! Distilled water contains none of those minerals that are needed for the yeast to ferment properly. Tap water generally meets these requirements but, if it contains chlorine, it will need to be boiled to remove that. Chloramine, which some municipalities use in their water, cannot be boiled out of the water, however.
Hard water from the tap can make a difference; it’s better-suited for pale ales while soft water has often been used for stouts. Still, it is important to take water minerals into account. Hard water, which has higher levels of dissolved calcium and magnesium, has a different effect on the final product than soft water does.
The minerals in water do affect the starch conversion in the mash phase of brewing, though not as much as the malts themselves do. A darker roasted grain can neutralize the higher pH in soft or alkaline water. An overly high pH level in the mash can cause undesirable flavors and sometimes makes beer taste lacking or somewhat dull.
Certain styles of beer – especially pilsners, British IPAs, and Irish stouts – were all heavily influenced by the kind of water available in the places in which they were first brewed. If you’re interested in recreating these beer styles, do your research; learnt only what kind of water was available to these brewers, but also how it was treated by the brewers before it was used. There’s always something new to learn from the masters!