Glossary
How to read a water label.
The same terms the quiz tooltips teach — collected, anchored, and said straight.
TDS — total dissolved solids
Every mineral in the water summed, in mg/L, usually measured as dry residue: evaporate a litre and weigh what is left. TDS is the loudness knob — under ~50 mg/L a water is barely there; over ~1,500 mg/L it is intensely mineral. It tells you how much is in the glass, not which minerals, so two waters with identical TDS can taste completely different.
The low/medium boundary used across the water world sits at 250 mg/L — that is where our "light" and "full body" split lives too.
Carbonation — natural vs added
Carbonation is dissolved CO₂, and still-versus-sparkling is the most perceptible fork in water. "Natural" means the gas rises with the water from a volcanic or deep geologic source; "added" means it is injected at bottling. The distinction is provenance — terroir, if you like — because CO₂ itself tastes much the same either way.
CO₂ also lowers pH slightly, which is where sparkling water's faint tang comes from.
Cation character — crisp vs savory
The dominant positive ion sets a water's temperament. Calcium and magnesium — hardness, dissolved from limestone and dolomite — read crisp, chalky, clean-edged. Sodium, typical of volcanic and thermal springs, reads soft, silky, faintly saline.
Dominance is decided the way hydrochemists do it: by milliequivalents (charge-weighted concentration), not raw milligrams. A water can contain plenty of sodium and still be calcium-dominant.
Anion character — round vs dry
The dominant negative ion shapes the finish. Bicarbonate (CO₂ reacting with carbonate rock) rounds and soothes — the classic "digestive" dinner waters. Sulfate, dissolved from gypsum, reads dry and faintly bitter, closer to a brut wine's finish, and is mildly laxative in quantity.
Most spring waters are bicarbonate-dominant; genuinely sulfate-dominant bottles are the rarer, drier shelf.
Magnesium — the tonic edge
Magnesium adds a bracing, slightly bitter edge — the classic spa and recovery mineral. You only start to taste it around 100 mg/L (that is sensitive palates; the average person needs several times more, per Health Canada's review), which is where our "bitter edge" line sits.
The EU lets any label above 50 mg/L say "contains magnesium" — a claim, not a flavor. Waters between 50 and 100 mg/L carry the label and taste of nothing much.
Silica — the beauty mineral
Silica (SiO₂) dissolves out of volcanic rock and is marketed for skin, hair and connective tissue — the entire Fiji/Volvic pitch. It has little proven effect on taste, and it is invisible to a standard TDS meter reading, which makes it a genuinely hidden compositional differentiator.
It is also the least-published mineral on labels. When a producer publishes no number, we say "not published" rather than estimate — a missing value is information too.
Sodium — the 20 mg/L line
Sodium is the salt in your water. Most bottled waters are low; thermal and "soda" springs can run 200–1,200 mg/L. The line that matters if you watch salt is 20 mg/L: below it, EU law (Directive 2009/54/EC) allows the claim "suitable for a low-sodium diet".
Taste-wise sodium is near-invisible low down and adds a savory edge high up — so choosing low-sodium costs nothing in flavor.
Virginality — nitrate as a purity proxy
A water-sommelier term for how untouched a source is, read through nitrate (NO₃): surface activity — agriculture, settlement — pushes nitrate up, so a deep, well-protected aquifer shows very little of it. Under ~1 mg/L is considered superior.
We report the published nitrate value (or the producer's detection limit) per water; it never affects matching, but it is one of the most honest single numbers about a spring's isolation.