Water: the invisible ingredient of coffee

When we talk about coffee, we usually focus on the origin, the process, the roast, or the recipe. But there's an element that often goes unnoticed, yet it influences everything: water. Not as a base, but as an ingredient. Because water doesn't simply accompany the coffee; it's the medium through which the coffee expresses itself . Approximately 98% of your cup is water, and its composition directly influences how the aromas, flavors, and body are expressed.

You can have great coffee and a good coffee maker, but if the water isn't up to par, the result will never be what it should be.

Why water matters so much

Water is the solvent responsible for extracting the soluble compounds from the coffee bean. For this to occur in a balanced way, the water needs to have the right mineral content . Water that is too hard or too soft can dull even the most expressive coffees.

• Water that is too hard : contains an excess of minerals. This can hinder even extraction and result in flat, harsh cups or cups with unwanted bitterness.

• Water that is too soft or distilled : it lacks the ability to properly extract the compounds from the coffee. The result is usually an empty cup, lacking structure and depth, and likely exhibiting high acidity.

Hardness is defined by the total amount of Mg²+ and Ca²+, although it is also important to take into account the presence of other dissolved substances such as minerals, salts, metals… and from that total number we can obtain the total amount of particles per million (ppm) present in the water.

The goal is to find the perfect balance for the extraction you're looking for.

The ideal composition: what to look for in water

On a practical level, there are some key factors you can consider when choosing or preparing your water:

• Magnesium : It attracts the smallest particles, which contribute to the aromatic nuances and flavor complexity. It helps to enhance sweetness and clarity. Recommended range: between 5 and 30 mg/L.

• Calcium : It binds more readily with heavier particles, making it primarily responsible for the tactile sensation in the mouth: texture, body, cleanliness… It's a great ally, but in excess it can dull nuances. Recommended range: between 10 and 50 mg/L.

• Sodium : Sodium can contribute to unwanted salty sensations and muddy the profile. Always aim for low amounts of it.

As a general guideline, many coffee recipes work well with water that has a TDS of around 70–150 ppm , although this will also depend on each bean and the method you use to extract it.

If you use bottled water, look for water with low mineral content . If you use tap water, a good filtration system can make a big difference, both in taste and consistency.

Hardness and extraction: the key balance

Water hardness is directly related to the way coffee is extracted.

Water with a balanced mineral content allows for more uniform extraction and for the coffee to express itself in a cleaner and more defined way.

Temperature is also water

It's not just what water you use that matters, but how you use it . Temperature is another key factor.

In general terms:

• The ideal extraction temperature is around 90°C .

• In immersion methods (such as French press or AeroPress), you can comfortably work in lower ranges.

• In drip brewing methods (V60, Kalita, batch brew), slightly higher temperatures will help with more complete extraction.

Too low a temperature can leave the coffee underextracted and flat. Too high a temperature can burn delicate flavors and accentuate bitterness.

Small adjustments, big changes

Improving the water you use to prepare coffee is probably one of the simplest and most effective ways to improve the cup result of the same coffee.

Filtering water, choosing better bottled water, or adjusting the temperature are small decisions, but with a huge impact. Ultimately, understanding water as another ingredient is a step forward in how we prepare and enjoy coffee.