I measured and tasted 18 water samples during my coffee-water tour. Here are the results, with some conclusions and recommendations.
One thing is certain: to further verify the results and arrive at scientifically sound statements, a larger panel of sensory experts who taste a larger quantity of water and coffee together in one place is needed. In this respect, my results are merely indicators.
Three new articles delve deeper into the topic of water for coffee:
- Good Water for Coffee
- Test of Water Filter Pads
- Test of Water Filter Cartridges and Filter Performance
Results
The most important insight for me is that there is a value range for good water. Depending on where the water used is located within this range, the taste results differ. However, they all remain in the good to very good range, only with different accents. Water that lies outside this value range is significantly less suitable for making coffee.
The graph shows my measurement results. The y-axis represents alkalinity or carbonate hardness, and the x-axis represents total hardness (both in °dH). Each point represents a water sample that I took and measured at one of 18 locations. All points in the light green area were rated by me with 82 to 84.75 points (according to SCAA/Q-Grader form). All points outside the light green area were rated lower (77 – 81.75). I tasted all waters at least twice via cup tasting and measured total hardness (GH), alkalinity (carbonate hardness), conductivity, and pH value.
Along the orange arrow, all waters perform well to very well.
In the area with low GH and alkalinity (approx. 3 °dH GH/2 °dH alkalinity), acidity is emphasized because it is buffered less by alkalinity. In the light green area, I perceived this as positive. The sweetness of the coffee also came out very well.
Further down in the left corner, i.e., with even lower alkalinity and outside the light green area, the coffee then tipped towards an excessive acidity that was no longer positive and complex, but aggressive and dominant. The acid-buffering capacity of alkalinity was missing. The acidity of the coffee (approx. 5.0 pH for coffee) came through completely. The flavor notes of the coffee were displaced by the acidity and were only recognizable in the background.
In the light green area of higher total hardness and alkalinity (approx. 8 °dH GH/5 °dH alkalinity), I perceived the acidity as less intense and complex, but still positively present and very balanced in interaction with the other attributes of the coffee. Here, the body of the coffee was emphasized and the texture was more noticeable. We owe this primarily to the total hardness (especially magnesium, but also calcium).
If you further refine the values and increase both total hardness and alkalinity, the following happens: The flavor potential of the coffee can no longer be tasted; the delicate nuances of the coffee are no longer fully extracted by the water, which is more saturated due to the higher total hardness, or they are lost alongside it. The coffee becomes flat and crude; the flavor complexity is lost. At the same time, the increased alkalinity buffers away the acidity and with it any vitality of the coffee.
Total hardness and alkalinity can be measured without much effort with titration tests. More on this below.
Remarks and Thanks
This description is superficial and lacks the necessary chemical explanations. These explanations are provided by the Kaffeemacher in the course "Water and Coffee Intensive". Also recommended is the reading of Maxwell Colonna-Dashwood's and Christopher Hendon's new book "Water for Coffee."
During the tastings, I used a washed Colombian coffee that was roasted relatively light with a Colorette of 133. The origin of the coffee and the roast play a big role in any case, but were not further included in these tests.
I paid less attention to the pH value of the water (although it was measured each time). With an alkalinity between 1.4 °dH and 5.85 °dH, the pH value only fluctuates between 6.6 and 7.5. Should the measurement deviate from this, it is recommended to boil the water and then test it again. The pH value then usually settles down.
My travel route led through Valais, Ticino, and Grisons. So I was mainly able to taste soft waters, which were predominantly good. I deliberately chose this route to be in a hypothetically good water area. The total hardness of many Swiss cities and regions can be checked via wasserqualitaet.ch.
I would like to thank Schaerer for supporting the tour, as well as BWT. With BWT, we as Kaffeemacher began a partnership in the spring to jointly develop training and exchange on the topic of water and coffee.
My sincere thanks also go to ZHAW, Prof. Chahan Yeretzian and Dr. Marco Wellinger. Their profound knowledge, their scientific support, and their constant willingness to support me and the Kaffeemacher with advice and action are a great enrichment for our work.
Thanks also to Philipp Henzen and the Rösterei Caffè Sempione in Termen. You were great hosts and your water is excellent.
Personal Conclusion
For me personally, this journey has broadened my understanding of water, and I have learned a lot. I was able to verify some hypotheses with sensory impressions and thus gain certainty.
At least as impressive for me was the journey through Switzerland. I am very touched by the encounters and landscapes in the cantons of Valais, Ticino, and Grisons and by the numerous magnificent waters that simply babble from the fountains.
How good is the water in your city or from your tap?
Wasserqualitaet.ch is a good help. However, the supply lines change, and the quality ultimately depends on the district. Therefore, a test always makes sense. Small titration tests are suitable for this. They are available online and now also from Kaffeemacher.
What to do if the water is not good?
There are two options. Filter or buy mineral water that fits within the values mentioned above. More on this and how to convert the information on the mineral water bottle will soon be available here on the blog.
If you want to find out more about the perfect water for coffee, you can find all our articles on the topic here.
