Water in Coffee: the most overlooked ingredient

When talking about specialty coffee, the conversation almost always revolves around origin, altitude, drying process, roast, machine, or grinder. But there's one element that remains undervalued, even among many professionals: water.

And that's strange when we realize a simple thing: a cup of coffee is composed of about 88% to 99% water. 

In other words, even the best coffee in the world can taste bland with the wrong water. And merely "good" coffee can be transformed with balanced water.

Water is not just a neutral vehicle. It is an active ingredient in extraction. The minerals present in it bind to the coffee compounds and determine what makes it, or doesn't make it, into the cup.

Why does water change the flavour?

The minerals present in water affect coffee extraction. Calcium, magnesium, and bicarbonates influence:

• sweetness;
• acidity;
• body;
• clarity;
• bitterness.

Water with excessively low mineralization can produce "empty" and flavourless coffees. Overly mineralized water can result in heavy, bitter cups lacking definition.

The importance of pH and TDS

pH indicates the level of acidity or alkalinity of the water. For coffee, ideal water is close to neutral, around pH 7.

TDS (Total Dissolved Solids) represents the total amount of dissolved minerals in the water. The Specialty Coffee Association recommends balanced values, usually around 150 ppm.

In Portugal, this value often appears on labels as "dry residue".

Ideal water for espresso and filter

In espresso, excessively hard water increases bitterness and limescale in the machine. In filter coffee, softer waters usually enhance floral notes, fruit, and clarity better.

Therefore, many baristas use filtration, osmosis, or specific waters to optimize extraction.

Water also affects the machine

Water quality doesn't just influence flavour. Very hard water creates deposits in boilers, valves, and groups, reducing stability and increasing maintenance costs.

And in Portugal?

Much of the water in Portugal, especially in the Lisbon area, has a relatively high hardness. This makes filtration particularly important for those seeking consistency and equipment longevity.

In specialty coffee, water is not a technical detail. It is one of the main ingredients in the cup.