Water in coffee
Water is one of the most overlooked ingredients in coffee. And considering it makes up more than 98% of a filter coffee and around 90% of an espresso, it deserves a little more attention.
Mineral content
The water you use affects how coffee extracts, how it tastes and even which flavours you are able to bring out. The same coffee can taste completely different depending on the water.
It all starts with minerals.
The minerals dissolved in water interact with the flavour compounds in coffee during extraction. Their balance and concentration can influence acidity, sweetness, body and overall balance.
For coffee, we can broadly think about water minerals in two groups: General Hardness (GH) and Carbonate Hardness (KH).
GENERAL HARDNESS (GH)
The two most important minerals for coffee brewing are magnesium and calcium.
Magnesium has a strong interaction with the natural acids in coffee. It can help bring out brighter, more pronounced flavours — think citrus, berries and other fruit-forward notes.
Calcium interacts a little less strongly with these acids. It tends to support softer, rounder flavours such as strawberry and cherry, while also contributing to a fuller sense of body.
CARBONATE HARDNESS (KH)
KH is mainly related to bicarbonate in the water. It acts as a buffer against acidity.
Too little buffering can make a coffee taste sharp or overly acidic. Too much can flatten the acidity and make the coffee taste dull, chalky or bitter.
The goal isn't simply to have more or fewer minerals. It's about finding the right balance for the coffee you're brew
CHOOSING YOUR WATER
Finding the right brewing water is arguably even more important than choosing your brewing method.
We recommend using a soft mineral water, with a Total Dissolved Solids (TDS) level of around 50 ppm. This provides a clean starting point that allows the coffee’s own flavours to shine without the water overpowering the cup.
If you're using bottled water, check the mineral composition on the label. If you're using tap water, a simple TDS meter can help you understand what you're working with.
Water temperature
Water temperature is another important part of the brewing equation. It directly affects how much you extract from the coffee — including both the flavours you want and the ones you don't.
In simple terms, hotter water extracts more, while cooler water extracts less.
For our coffees, we generally recommend starting around 94–96°C when the coffee is perfectly rested. This higher temperature can help bring out more clarity, complexity and intensity.
If the coffee is still relatively fresh, try lowering the temperature to around 90–92°C. A lower temperature can give you a more balanced and sweeter cup, with a slightly softer and more muted expression.
Temperature can also be particularly useful when brewing anaerobic coffees. These coffees can have intense, funky and highly expressive flavours. Brewing at a lower temperature can help keep those flavours in check and produce a more balanced cup.
Resting process
Freshly roasted coffee needs time. During roasting, gases — mainly CO₂ — are created inside the coffee bean. After roasting, these gases slowly escape in a process called degassing.
For dense, high-grown coffees, especially lightly roasted coffees, this process can be surprisingly slow. The tight structure of the bean holds onto these gases for longer, meaning that the coffee can continue to change significantly for weeks after roasting.
As coffee rests, harsh and astringent flavours gradually soften. What can initially taste like a "roasty" or slightly rough character gives way to a cleaner, brighter expression of the coffee.
That's why we recommend resting our coffees for at least 10 days. And don't be afraid to wait longer: with particularly dense coffees, we often find excellent results even beyond 5 weeks after roasting.