Plate XIV · section 13 of 13

Today

Since 2018, coffee water has become a product that is bought.

First, sachets of minerals to dissolve, with Third Wave Water in 2016. Then remineralizing pitchers, with Peak Water in 2019. And since 2023, launched in Australia, liquid concentrates in drops.

The latter offer four taste profiles, built on chlorides, magnesium sulfate, bicarbonates and sometimes silica. The dosage is 3 to 4 g per liter, or one to ten drops in a 200 mL cup.

Is it a laboratory fad? Not only: the great majority of finalists at the 2025 World Brewers Cup say they used it.

Research follows. The Zurich center of excellence, the ZHAW, keeps publishing, and the SCA has built water into its Coffee Value Assessment.

But a gap remains, and it is instructive. The effect of anions, potassium and pH has still not been isolated by a controlled study. The reason is physical: they cannot be varied without touching the rest. Change the pH, and you change the bicarbonate balance. Add an anion, and you necessarily add a cation with it. Some questions resist experiment, not for lack of interest, but because nature refuses to isolate them.

Apax Lab, product pages (2026); Third Wave Water; Peak Water; Gagné 2021, pp. 24-25 and 33; Gagné 2018, pp. 3-4

Gray areas

What the sources do not allow us to assert. We say so rather than filling the gap.

That magnesium extracts different flavors from calcium is widely accepted in the trade, but no laboratory test proves it in coffee; the chromatography data are a hypothesis about diffusion (Gagné 2021, p. 24; Gagné 2018, p. 3).
Other trials measured no difference in extraction yield when varying hardness (Smrke, pers. comm., cited by Gagné 2021, pp. 24-25): the effect would be a modulation of taste, not of extraction.
The effect of anions, chloride against sulfate, of potassium and of pH has not been isolated: they cannot be varied without touching the rest (Gagné 2021, pp. 28-29 and 33).
The preference for 20 ppm of alkalinity (Wellinger and Yeretzian 2015) may have been measured on a coffee roasted darker than the specialty average; it does not transpose as is to light roasts (Gagné 2021, p. 24).
The calculator's profiles are targets set by the author of the site, inspired by the published recipes and the declared compositions of commercial concentrates; manufacturers do not publish their concentrations, and the taste descriptions are commercial claims, not measurements.
Cheap TDS meters are accurate to 30% at best and say nothing about alkalinity (Wellinger, Smrke and Yeretzian 2017); aquarium kits do not specify where, in the color transition, their endpoint falls.
The hardness and alkalinity of Paris water are calculated here from the mineral content table published by Eau de Paris, not read from an official report in French degrees.

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In this plateThe 13 sections

The table of contents, with the first sentence of each section

The plant

From fruit to cup

The world of coffee

The body and matter

Start with the plant

Four stories

Five tools

The site

Today