Water is a fundamental element in the preparation of coffee. A brew contains 98% water; its hardness, that is, the amount of minerals the water contains, has a direct impact on the extraction of the best attributes of the coffee beans.
Water hardness is linked to the calcium, magnesium, iron, chlorine, fluoride and salts that it contains. The higher the concentration of these minerals, the harder the water is; if the concentration is lower, the water is softer.
Water with a mineral concentration of below 100 parts per million (ppm) is considered soft whereas water with more than 300 ppm falls into the hard water category. It is recommended that the mineral component of the water be under 250 ppm to guarantee a successful extraction.
In general, soft water adds too much acidity and not enough body. Hard water, on the other hand, produces bitterer notes and a heavier body.
The concentration of minerals, such as limescale, affects the quality of the coffee in the cup, since an excess of these elements saturates the water and leaves less space for the compounds that provide flavor.
These calcareous components also build up in coffee makers and hinder their performance, which is why they must be descaled frequently with tablets or a special liquid.
Conversely, water with few minerals is often very acidic and deteriorates the metal in the coffee pot, causing metal particles to come out in the drink.
Water hardness, both tap and bottled, significantly affects the taste of the coffee and the condition of the coffee makers. For this reason it is important to seek expert advice to analyze the water you use to ensure it is of the highest quality possible for your brewing process.