Making a truly great cup of coffee requires great beans, an expert roaster, the right grind, and proper technique. But an often-overlooked element of brewing coffee at home is what constitutes perhaps 99% of the delicious drink's weight: Water. If you live in a hard water area, try buying a small bottle of mineral water to brew a single cup of coffee. Brew another coffee straight afterward in exactly the same way but using regular tap water instead. From seasoned coffee taster to interested novice, every person who has ever compared the two has been shocked at the difference in quality.
Role of water
Water is a vital ingredient in a cup of coffee as it makes up around 90 percent by volume of espresso and 98.5 percent of a cup of filter coffee. If the water doesn’t taste good to start with, neither will the cup of coffee in the end. And if you can taste the chlorine, the resulting cup of coffee will be terrible. In many cases, a simple water filter jug that contains active carbon (such as a Brita filter) will do a good job of removing negative tastes, but it still might not produce the perfect water for brewing coffee.
Water acts as a solvent, doing the work of extracting the flavors in the coffee during the brewing process. This is where the quality of the water plays a major role, as the hardness and the mineral content can significantly affect how the coffee brews.
Why water hardness matters so much for brewing coffee
Water hardness is a measure of how much limescale (calcium carbonate) is dissolved in the water. choosing the right hardness for water remains a controversial topic, PEOPLE were having problems with coffee that tasted good one day and not another.
Aside from a good flavor and just a little hardness. There isn’t too much else we really want in the water, but the relatively low mineral content is desirable. Whether it is water coming from the local water supply or from bottled water, its main elements are:
- Natural minerals; coming from the ground or absorbed during its journey from source to tap.
- Chemical substances; used to treat water to make it microbiologically pure and free from bacteria, mainly chlorine.
It is this chlorine that is coffee’s number one enemy due to its oxidizing effect that alters the sensory structure of the coffee making it more bitter and, in the case of espresso, bleaching the creamy layer on the surface of the coffee. To eliminate it one needs to use active carbon filters or simply leave the water to rest for a period of time, given that chlorine tends to evaporate rather quickly. Manufacturers of mineral water are required to list the mineral content on the bottle and it is usually described as the total dissolved solids (TDS), or the dry residue at 180°C (365°F)
Choosing A Perfect Water
Besides the actual coffee that you select to brew with, water is the most important element that goes into a cup of coffee. The mineral content and ph level of the water you use can have drastic effects on the finished product. Using the wrong water can ruin a beautiful coffee and nobody wants to see that happen.
James Hoffman, 2018, 'The World Atlas Of Coffee', water for brewing vol. 34, no. 2, pp. 72-73