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.

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 the case

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 (Brita, BWT) 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. The filter was one of our first investments — and one of the most sensible ones. I always recommend a water filter to guests in Berlin. The hardness here is too high for unfiltered brewing.

Related Questions

• How important is water quality for good coffee?
• Which water hardness is ideal for coffee?
• Brita or BWT: Which water filter is better for coffee?

More depth on this topic can be found in our article Buying and using a filter coffee machine. Or stop by at Sophienstraße 27 — Mon–Fri 8am–5pm, Sat 10am–5pm.