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 conclusions, a larger panel of sensory experts is needed who taste a larger quantity of water and coffee together in one location. In this respect, my results are only indicative.
Three new articles delve deeper into the topic of water for coffee:
- Good water for coffee
- Testing water filter pads
- Test of water cartridges and filter performance
Results
The most important insight for me: there is a range of values for good water. Depending on where the water falls within this range, the taste results vary. However, they all remain within the range from good to very good, with different accentuations. Water that falls outside this range is significantly less suitable for making coffee.
The graph shows my measurement results. The y-axis represents alkalinity or carbonate hardness, while the x-axis represents total hardness (each in °dH). Each point represents a water sample that I took and measured at one of 18 locations. I rated all points in the light green area with a score between 82 and 84.75 (according to the SCAA/Q-Grader form). I rated all points outside the light green area lower (77 – 81.75). I tasted all water at least twice via cup tasting and measured total hardness (GH), alkalinity (carbonate hardness), conductivity, and pH.
Along the orange arrow, all waters perform well to very well.
In the range with low GH and alkalinity (approx. 3 °dH GH/2 °dH alkalinity), the acidity is emphasized because it is less buffered by the alkalinity. I perceived this as a positive aspect in the light green area. The sweetness of the coffee also came through very well.
Further down in the left corner, with even lower alkalinity and outside the light green area, the coffee then tipped toward an overflowing acidity that was no longer positive and complex, but aggressive and dominant. The acid-binding power of alkalinity was missing. The coffee's acidity (approximately 5.0 pH for coffee) completely overpowered the coffee's flavor notes. The acidity was displaced by the acidity and was only detectable in the background.
In the light green range 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 rest of the coffee's attributes. Here, the body of the coffee was more pronounced and the texture more noticeable. This is primarily due to the total hardness (primarily magnesium, but also calcium).
If you increase the values further and increase both the total hardness and the alkalinity , the following happens: The coffee's flavor potential can no longer be tasted, the coffee's subtle nuances are no longer fully extracted by the water, which is more saturated due to the higher total hardness, or they are drowned out by it. The coffee becomes flat and lumpy, and the flavor complexity is lost. At the same time, the increased alkalinity buffers the acidity and thus any vitality of the coffee.
Total hardness and alkalinity can be measured easily using 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 coffee makers in the " Intense Water and Coffee " course. We also recommend reading Maxwell Colonna-Dashwood and Christopher Hendon's new book, "Water for Coffee."
For the tastings, I used a washed Colombian coffee that was roasted relatively lightly with a colorette of 133. The origin of the coffee and roasting always play a significant role, but were not further considered in these tests.
I paid less attention to the water's pH (although I did measure it on occasion). With an alkalinity between 1.4 °dH and 5.85 °dH, the pH fluctuates only between 6.6 and 7.5. If the measurement deviates from this, it's recommended to boil the water and then test again. The pH will then stabilize in most cases.
My route took me through Valais, Ticino, and Graubünden. So, I was able to sample mostly soft water, which was mostly good. I deliberately chose this route to travel through a hypothetically good water area. The total hardness of many Swiss cities and regions can be checked at wasserqualitaet.ch.
I would like to sincerely thank Schaerer for supporting the tour, as well as BWT. I've been working closely with Schaerer since the 2014 Brewers Cup, and I share my colleagues' enthusiasm for continuing to explore coffee. As coffee makers, we began a partnership with BWT this spring to jointly develop training and exchanges on the topic of water and coffee.
My sincere thanks also go to the ZHAW, Prof. Chahan Yeretzian, and Dr. Marco Wellinger. Their in-depth knowledge, their scientific support, and their constant willingness to support me and the coffee makers with advice and assistance are a great asset to our work.
Thanks also to Philipp Henzen and the Caffè Sempione roastery in Termen. You were wonderful hosts, and your water is fantastic.
Personal conclusion
For me personally, this trip broadened my understanding of water, and I learned a great deal. I was able to verify some hypotheses with sensory impressions, thus gaining confidence.
The trip through Switzerland was at least as impressive for me. I was deeply moved by the encounters and landscapes in the cantons of Valais, Ticino, and Graubünden, and by the numerous magnificent streams of water that simply trickle out of the fountains.
How good is the water in your city or from your tap?
Wasserqualitaet.ch is a good resource. However, water supply lines vary, and the quality ultimately depends on the district. Therefore, testing is always a good idea. The small titration tests are ideal for this. They are available online and now also at coffee shops .
What to do if the water is not good?
There are two options: filter it or buy mineral water that meets the above-mentioned values. More on this, including how to convert the information on the mineral water bottle, will be available soon on this blog .
If you want to find out more about the perfect water for coffee, you can find all our articles on the topic here.
