I measured and tasted 18 water samples during my coffee-water tour. Here are the results, along with some conclusions and recommendations.
One thing is certain: to further verify the results and arrive at scientifically sound statements, we need a larger panel of sensory experts tasting a larger quantity of water and coffee together in one location. In that sense, my results are merely indicative.
Three new articles delve deeper into the topic of water for coffee:
- Good water for coffee
- Test of water filter pads
- Test of water cartridges and filter performance
Results
The most important finding for me: there is a value range for good water. Depending on where within this range the water used falls, the flavor results vary. However, they all remain in the range of good to very good, just with different accents. Water that falls outside the value range is significantly less suitable for making coffee.
The graphic shows my measurement results. The y-axis represents alkalinity or carbonate hardness, the x-axis represents total hardness (each in °dH). Each point represents a water sample that I took and measured at one of 18 sampling locations. All points in the light green area, I rated with 82 to 84.75 points (according to SCAA/Q-Grader form). All points outside the light green area I rated lower (77 – 81.75). I tasted all waters at least twice via cupping 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), the acidity is emphasized because it is buffered less by the alkalinity. In the light green area, I perceived this as positive. The sweetness of the coffee also came through very well.
Further down in the left corner, so with even lower alkalinity and outside the light green area, the coffee then tipped towards an overwhelming acidity that was no longer positive and complex, but aggressive and dominant. It lacks the acid-buffering capacity of alkalinity. The acidity of the coffee (approx. 5.0 pH in coffee) came through completely. The flavor notes of the coffee were overtaken by the acidity and were barely discernible in the background.
In the light green area with 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 interplay with the other attributes of the coffee. Here the body of the coffee was emphasized and the texture more perceptible. We have the total hardness to thank for this above all (especially the magnesium, but also the calcium).
If you further sharpen the values and drive both total hardness and alkalinity upward, the following happens: the flavor potential of the coffee is no longer noticeable, the subtle nuances of the coffee are no longer fully extracted by the water that is more saturated due to the higher total hardness, or they are overshadowed by it. The coffee becomes flat and dull, 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 using a titration test. More on that below.
Notes and Thanks
This description is superficial and lacks the necessary chemical explanations. These explanations are provided by the coffee makers in the course "Water and Coffee Intensively". Also recommended is reading Maxwell Colonna-Dashwood's and Christopher Hendon's new book "Water for Coffee"
For the tastings, I used a washed Colombian coffee that was roasted relatively light with a Colorette of 133. The origin of the coffee and roast play a major role in any case, but were not further factored into 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 fluctuates only between 6.6 and 7.5. Should the measurement deviate from this at some point, it is recommended to boil the water and then test again. The pH value usually settles in most cases.
My travel route took me through Valais, Ticino, and Graubünden. So I was mainly able to taste soft waters, which were predominantly good. I chose the route deliberately 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 the Schaerer company very much for supporting the tour, as well as the BWT company. I have worked closely with Schaerer since the Brewers Cup 2014 and share with my colleagues the enthusiasm to continually engage further with coffee. With BWT, we coffee makers began a partnership in spring to develop training and exchange on the topic of water and coffee together.
My sincere thanks also go to ZHAW, Prof. Chahan Yeretzian, and Dr. Marco Wellinger. Your well-founded knowledge, your scientific support, and your constant willingness to support me and the coffee makers with advice and action are a great enrichment for our work.
Thanks also to Philipp Henzen and the roastery Caffè Sempione in Therme. You were wonderful hosts and your water is top-notch.
Personal Conclusion
Through this trip, the topic of water has opened up for me personally and I have learned a lot. I was able to verify some hypotheses with sensory impressions and thus gain confidence.
Equally impressive for me was the trip through Switzerland. I am very moved by the encounters and landscapes in the cantons of Valais, Ticino, and Graubünden and by the numerous magnificent waters that simply flow out of 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 is ultimately neighborhood-dependent. Therefore, a test is worthwhile in any case. The small titration tests are suitable for this. Available online and now also with the coffee makers.
What to do if the water is not good?
There are two options. Filter or buy a mineral water that fits into the values mentioned above. More on that and how to convert the information on the mineral water bottle, coming soon here in the blog.
If you want to learn more about the perfect water for coffee, you can find all our articles on the topic here.
