When a coffee tastes of nothing, we blame the blend or the machine. But there's one ingredient we almost always forget, and which makes up over 90% of what we drink: water. Water quality affects the taste in the cup just as much as the coffee itself. Let's see why, and how to choose the right one.
Why water matters so much
Water is the solvent that extracts aromas, oils and soluble substances from the ground coffee. Its composition determines which molecules are extracted and in what quantity. The "wrong" water can flatten the aromas, heighten bitterness or acidity, and over time ruin the machine with limescale. That's why barista championships use water calibrated to the milligram.
Hardness, mineralization and pH
Hardness
Hardness indicates the amount of dissolved calcium and magnesium salts. It's the most important factor:
- Water that's too hard (very chalky): extracts poorly, tends to mute the aromas and deposits limescale in the machine.
- Water that's too soft (almost distilled): extracts in an unbalanced way and gives "empty", flat cups.
- The middle ground: water with medium-low hardness is ideal, because it extracts in a balanced way.
Dry residue
On the label of mineral waters you'll find the dry residue at 180 °C: this is the amount of minerals. For coffee, low-mineral (oligomineral) waters are preferred, with a dry residue roughly between 50 and 150 mg/l. "Very low mineral content" waters (under 50) tend to give flat coffees, while those very rich in salts weigh it down.
pH
The ideal is water with a neutral pH (around 7). Waters that are too acidic or too alkaline alter the balance of the coffee.
Which water to use at home
- Tap water: it works perfectly well if it's low in limescale in your area. In many southern cities and in chalky areas, however, it's "hard" and it's worth filtering it.
- Bottled mineral water: choose a low-mineral water with low dry residue (check the label). It's the simplest choice for a consistent result.
- Filtered water: a jug with an activated carbon filter or a small softener reduces limescale and chlorine, improving the taste and the life of the machine.
Avoid using water that has already been boiled or has been sitting in the tank for days: "old" water loses oxygen and gives a dull coffee.
Water and limescale: protect your machine
The harder the water, the faster limescale forms in the pipes and the boiler. Limescale slows down the flow, alters the temperature and, in the long run, damages the machine. Using low-residue water and descaling regularly (every 1-3 months) extends the life of your appliance and keeps the coffee good.
Practical tips for every method
- Capsule/pod machine: fill the tank with fresh low-mineral or filtered water; empty it if it goes unused for a long time.
- Moka pot: use water with a low limescale content and pour it straight into the boiler without going past the valve. Some prefer it slightly warm to shorten the time on the stove.
- Travelling or at the office: if the local water is awful, a bottle of low-mineral water works wonders on your cup.
In conclusion
You can have the best blend in the world, but without the right water it will never perform at its best. Go for fresh, low-residue, neutral-pH low-mineral water, and protect the machine from limescale. It's the simplest and cheapest way to improve every coffee. In our catalogue you'll find pods, capsules and coffee beans from the best Italian roasters: give them the water they deserve and you'll taste the difference.
