Do I need a water filter for my coffee machine?
In areas with water hardness over 14 °dH (Berlin, Munich, Stuttgart), a filter is highly recommended — for better taste and longer machine lifespan. With soft water under 8 °dH, it is mostly unnecessary.
Why that is
A water filter for your coffee machine serves two functions: it improves the taste of your coffee and protects your machine from limescale buildup. Whether a filter is worth it depends on your local water hardness.
Taste. Hard water contains a lot of calcium and magnesium, but above all a high carbonate hardness. This carbonate hardness neutralizes the fine acids in the coffee, which are responsible for fruitiness and liveliness. The result: your coffee tastes flat and dull, no matter how good the beans are. A filter reduces the hardness and lets the beans show off their full potential.
Machine protection. Limescale builds up in pipes, heating elements, and valves. In espresso machines, this can become expensive — descaling in hard water areas is necessary every 2–4 weeks, and aggressive descalers damage seals and coatings over time. A filter significantly extends the descaling intervals and reduces wear and tear.
When a filter makes sense:
- Water hardness over 10–14 °dH (most of Germany)
- Espresso machine or fully automatic coffee machine in use
- Water tastes like chlorine or has a distinct off-flavor
When a filter is less necessary:
- Water hardness under 8 °dH (parts of Northern Germany, Black Forest)
- Only simple brewing methods without a machine (French Press, Pour-Over)
- Water tastes neutral and soft
For filter coffee machines and fully automatic machines, a table water filter is a good starting point. The water is filtered before filling the tank. For portafilter machines, under-sink filters that connect directly to the water line are recommended — they provide more consistent results and need to be replaced less frequently.
In practice at Green Wall Coffee
In Berlin-Lichtenberg, we have hard water (approx. 16 °dH). Without a filter, the taste from our espresso machine would be noticeably flatter, and descaling would be a constant issue. I always recommend a water filter to guests in Berlin. The hardness here is too high for unfiltered brewing.
You'll find us at Sophienstraße 27 in Berlin-Lichtenberg, Monday to Friday 8am–5pm and Saturday 10am–5pm.
Further reading
In-depth article: How to Make Perfect Espresso · Pour-Over Guide (V60)
Related questions:
- Brita or BWT: Which water filter is better for coffee?
- Should I use distilled water for coffee?
- What does Third Wave Water mean?
Also relevant:
- Is a water filter worth it in a fully automatic machine? — Super-Automatic Machines
- Why is water more important than the machine? — Espresso Preparation (Portafilter)
- What water does Green Wall Coffee use for its coffee? — Green Wall Coffee in Detail
All questions in this topic: Water & Water Quality