Pour two glasses of bottled water side by side. They look identical and both say water on the label, yet one can taste of almost nothing while the other lands with a chalky weight and a faint bitter edge. That gap is not marketing. It is dissolved rock, and a water can carry a great deal of it or next to none.
The number that tells you how much
Every mineral a water picks up underground gets added into a single figure, its total dissolved solids, or TDS, in milligrams per litre. Think of it as the volume knob. Voss from Norway sits at 44 and Spa Reine from Belgium at 33, barely there. Gerolsteiner from the volcanic Eifel carries 2,500. Donat Mg from Slovenia, which people drink by the small glass as a mineral supplement, holds more than 13,000. Lightest to heaviest, that is a spread of four hundred times, all of it sold as the same thing.
Weight is not the same as character
TDS only tells you how much is dissolved, never what. Two waters of the same weight can taste nothing alike, because flavour comes down to which ions win. Calcium and magnesium, leached out of limestone, read crisp and clean. Sodium, the mark of deep thermal springs, reads soft and faintly savory. On the finish, bicarbonate rounds things off, while sulfate out of gypsum dries the mouth and leaves a bitter edge close to a brut wine.
Two heavyweights make the point. Vichy Catalan from Spain is almost all sodium and bicarbonate, 1,097 mg/L of salt in a sparkling water that genuinely tastes of it, and it startles anyone expecting something neutral. Contrex from France goes the other way, a still water loaded with sulfate and calcium that finishes chalky and dry. Same heft, opposite waters.
Where the sommelier comes in
Wine has terroir, the idea that ground and climate leave a signature in the glass. Water has it too, only spoken more quietly. A water sommelier is trained to read that signature, to taste a bottle blind and place its weight and its source. In restaurants that keep a water list the job is real work, pairing a still or a sparkling to a dish the way a wine is paired, so the water flatters the food rather than fighting it.
At the top end it is theatre, and easy enough to laugh at. The point underneath is not. There are more than six hundred bottled waters in our catalog across sixteen distinct types, and most people drink whichever one the shop happened to stock, never once told the choice was real. When we print a number, we show where it came from.
You already have a preference
You do not need a sommelier at the table to drink better. You need the handful of words the trade uses for what you already like. Heavy or light. Still or sparkling. A crisp mineral edge, or something soft and round. Our quiz asks exactly that across seven swipes, then hands you a real bottle and the published analysis behind it. The sommelier’s read, in under a minute.