Fresh beans, proper grind, exact dose—and yet the filter coffee tastes flat. Round, but missing the fruit mentioned on the bag. In Munich, it’s worth taking a look at something most people don’t even see as an ingredient: the tap water.
In short: Munich tap water is hard. According to Stadtwerke München, the average total hardness is 15.8 °dH, and the carbonate hardness is 15.3 °KH. The high carbonate hardness, in particular, buffers the acid in the coffee, which is why light, fruity roasts often taste duller as a result. A table water filter for hard water or low-mineral still water can noticeably improve the outcome.
Coffee is almost entirely water—and tap water is rarely neutral
Filter coffee consists of about 98% water, espresso of around 90%. Tap water almost always contains dissolved minerals, primarily calcium, magnesium, and bicarbonate. These influence how coffee is extracted and how we perceive acidity, sweetness, and body.
As a guide, the 2009 water standard of the former SCAA (Specialty Coffee Association of America) is still frequently cited today. Its target values:
| Parameter | Target Value (SCAA Standard 2009) |
|---|---|
| Total Dissolved Solids (TDS) | 150 mg/l (Range 75–250 mg/l) |
| Calcium Hardness | 68 mg/l as CaCO₃ |
| Alkalinity | 40 mg/l as CaCO₃ |
| pH Value | 7.0 (Range 6.5–7.5) |
| Sodium | 10 mg/l |
| Chlorine | 0 mg/l |
These are guidelines, not hard limits. However, they indicate the direction in which good coffee water should lean: moderately mineralized, with low acid buffering.
We also taste every batch after roasting before it goes into the bag. How a coffee tastes depends partly on the water used.
Munich's 2026 water values in comparison
Munich’s drinking water comes largely from the Mangfall and Loisach valleys and is of very high quality. Stadtwerke München publishes the analysis values for the entire city area. As of January 2026:
| Value | Minimum | Average | Maximum |
|---|---|---|---|
| Total Hardness | 13.9 °dH | 15.8 °dH | 17.9 °dH |
| Carbonate Hardness | 12.2 °KH | 15.3 °KH | 17.4 °KH |
| Calcium | 67.6 mg/l | 78.0 mg/l | 87.0 mg/l |
| Magnesium | 18.6 mg/l | 20.9 mg/l | 24.8 mg/l |
| Bicarbonate | 258 mg/l | 324 mg/l | 368 mg/l |
| pH Value | 7.42 | 7.56 | 7.78 |
| Sodium | 5.0 mg/l | 5.9 mg/l | 6.7 mg/l |
To compare the values with the SCAA standard, they must be converted to the same unit:
- Calcium Hardness: 78 mg/l of calcium is mathematically equivalent to about 195 mg/l of CaCO₃. That is almost three times the target value of 68 mg/l.
- Carbonate Hardness (Alkalinity): 15.3 °KH is equivalent to about 273 mg/l of CaCO₃. That is almost seven times the target value of 40 mg/l.
Measured against the target value, the deviation for carbonate hardness is significantly greater than for calcium hardness.
Why carbonate hardness affects flavor the most
Bicarbonate buffers acid. In small amounts, this is good; otherwise, coffee tastes sharp. At the concentration found in Munich tap water, a portion of the acidity that gives light roasts their vibrancy is neutralized.
You will notice this most clearly with our filter coffees. TIKI TAKA from Ethiopia (Guji) thrives on jasmine, bergamot, and peach; PLAYMAKER from Kenya on blackcurrant and red berries. When brewed with very hard water, these notes can recede, and the coffee often appears rounder and heavier. Darker espresso roasts featuring chocolate and nut notes are generally less sensitive because their profile is less reliant on acidity.
And magnesium? A study by the University of Bath (Hendon et al., 2014) used computer models to calculate how strongly sodium, magnesium, and calcium bind to individual flavor compounds in coffee. The results are often interpreted to mean that magnesium extracts particularly well. This is a model calculation, not a taste test. Later laboratory tests found barely any differences in the amount of extracted acids at typical mineral concentrations. It is possible that minerals more likely influence how we perceive acidity and fruitiness. For practical purposes in Munich, there is a strong case for addressing carbonate hardness first, as it is the furthest from the target value.
When I first truly paid attention to water
For a long time, water wasn't a topic for me. When roasting, I focus on temperature, time, and color, but water simply came out of the tap.
That changed during a roasting course. After roasting, there was a cupping session, and the focus was specifically on the question of how much flavor really comes from the roast. The same light Ethiopian roast was prepared with three different waters, while keeping grind, temperature, and brew time identical. With the softer water, the bergamot was clearly detectable, almost like in tea. With the hard tap water next to it, it was barely noticeable.
Since then, for me, water is as much a part of the recipe as the grind and temperature. Even a good roast needs suitable water to show what it is capable of.
Better coffee water in Munich: three options
1. Table water filters for hard water
The most practical solution for everyday use. It is important to have a cartridge that reduces carbonate hardness and is designed for hard water, such as the BRITA MAXTRA PRO Limescale Expert. According to BRITA, the cartridge should be changed at least every four weeks—or sooner with hard water like Munich's, as the lifespan of the cartridge is reduced. A table filter does not guarantee SCAA values. The extent to which it reduces carbonate hardness depends on the source water, the cartridge, and usage. However, it addresses the value that is furthest from the target in Munich.
2. Low-mineral still water
Good for experimenting because you don't need to buy any equipment. Check the label for low bicarbonate content and low sodium. Highly mineralized medicinal or mineral waters are usually less suitable for coffee.
3. Distilled water with mineral concentrate
For those who want to compare accurately. Mineral packets like Third Wave Water are added to distilled water and, with precise dosage, result in a consistent composition. Pure distilled water, on the other hand, is usually not a good choice; more on that in the questions below.
The quickest way to find out if the effort is worth it for you is a direct comparison: the same coffee, drunk side-by-side, once with tap water and once with filtered water. With a light, fruity filter coffee, the difference is most apparent.
Frequently asked questions about water and coffee in Munich
Is Munich tap water bad for coffee?
No. It is a very high-quality drinking water in terms of hygiene and taste. However, for coffee, it is hard, with an average carbonate hardness of 15.3 °KH (SWM, January 2026). This primarily dampens the acidity of light roasts.
What water hardness is ideal for coffee?
There is no single ideal number. The 2009 SCAA standard is frequently cited, with approximately 68 mg/l calcium hardness and 40 mg/l alkalinity, each as CaCO₃. Converted, that is about 3.8 °dH and 2.2 °KH, respectively.
Is a BRITA filter sufficient for specialty coffee?
As a first step, yes, provided the cartridge is intended for hard water and is changed regularly. A filter does not guarantee exact target values. How much the carbonate hardness drops depends on the source water, the cartridge, and usage.
Can I use distilled water for coffee?
Purely, likely not. Without minerals and without acid buffers, coffee often tastes thin and sharply acidic. However, used as a base with an appropriate mineral concentrate, distilled water can work well.
Does boiling the water help?
Only to a limited extent. When boiling, a portion of the carbonate hardness precipitates as limescale, but this happens uncontrollably and, in Munich, is usually not enough to reach the target values.
Does water also play a role in espresso?
Yes. Bicarbonate buffers acidity in espresso as well. Furthermore, hard water deposits limescale in the boiler and pipes of the machine. This is why many manufacturers of portafilter machines recommend treated water.
Conclusion
Munich tap water is excellent drinking water, but too hard for coffee. The decisive value is carbonate hardness: it is about seven times above the SCAA target value and robs especially light roasts of some of their acidity. If you want to change that, the easiest way to start is with a filter for hard water and a direct comparison in the cup.
About the author: Jovana is a professional soccer player, owner of Nine Fine Roastery in Munich, coffeeologist, and roaster. She roasts the coffee for Nine Fine herself.
Sources: Stadtwerke München – Munich drinking water analysis values, as of January 2026 · SCAA Standard "Water for Brewing Specialty Coffee" (2009) · Hendon, C. H., Colonna-Dashwood, L., Colonna-Dashwood, M. (2014): The Role of Dissolved Cations in Coffee Extraction. Journal of Agricultural and Food Chemistry 62 (21) · BRITA – FAQ on filter cartridges
