The difference between spring water, mineral water, and purified water
The words on a water label are not marketing. In the United States they are legal categories defined by the Food and Drug Administration, and they turn on two things: where the water comes from and how much dissolved mineral it carries. Price does not enter into it. A refined spring water can sit below the mineral threshold while a more modest bottle clears it. Here is what the terms mean, why total dissolved solids change how a water tastes, and how the waters we carry sort themselves out.
What the labels legally mean
Under the FDA standard of identity (21 CFR 165.110), the categories are precise. Spring water is derived from an underground formation from which water flows naturally to the surface; it must be collected at the spring itself or through a borehole that taps the same formation. Mineral water contains not less than 250 mg/L total dissolved solids (TDS), coming from a geologically and physically protected underground source, and no minerals may be added. That 250 mg/L figure is the dividing line: below it a water cannot be called mineral water in the US, however clean its source. Purified water is produced by distillation, deionization, reverse osmosis, or a similar process, carries very low TDS, and may be labeled by its method (for instance "distilled" or "reverse osmosis").
The European framework treats the top category differently. "Natural mineral water" must come from a protected underground source, be bottled at source, and hold a stable, characteristic mineral composition. Nothing may be removed or added, except for regulated adjustments to carbonation. The emphasis is on constancy: a European natural mineral water should read the same, bottle after bottle, year after year, because its geology does not change on a human timescale.
What TDS is and why it changes taste
Total dissolved solids is the combined weight of everything the water carries in solution, principally calcium, magnesium, sodium, bicarbonate, sulfate, and chloride, measured in milligrams per litre. It is the single most useful number on a mineral analysis, and it maps closely onto what you taste. Low TDS drinks light and clean, with little to get in the way. Higher TDS reads fuller and rounder, and past a point it turns savory or frankly saline. A water is not better for carrying more, or for carrying less; the figure simply tells you which register it occupies. We keep a fuller explanation of the measurement on our page on what TDS in water means.
How the source geology shapes the water
A water's mineral profile is a record of the rock it moved through. Limestone terrain gives calcium and bicarbonate, the signature of Alpine and Tuscan sources that filter slowly through carbonate stone. Volcanic and granite ground leave different fingerprints, often lower in bicarbonate and shaped by the particular chemistry of the bedrock. This is why two mineral waters at similar TDS can taste nothing alike: the total is the same, but the constituents that make it up are drawn from different geology. When we read a water's own analysis we look past the headline number to its calcium, magnesium, and bicarbonate, and choose for distinction rather than sameness. For a worked example, see where Acqua Panna comes from.
Where the waters we carry fall
By the FDA thresholds, our catalog sorts cleanly. Acqua Panna, from Tuscany at roughly 130 mg/L, is spring water: it sits below the 250 mg/L line and cannot legally be called mineral water in the US, refined as it is. The mineral waters clear that line and then spread across a wide range. Evian, from the French Alps, runs about 357 mg/L. Perrier, from Vergeze, is near 475 mg/L. S.Pellegrino, from Lombardy, sits around 970 mg/L. San Benedetto, from the Veneto, just clears the threshold at about 254 mg/L. At the far end, Vichy Catalan, from Catalonia, is published near 3,052 mg/L, an emphatically saline water that shows how much range the single word "mineral" contains.
Purified waters are a separate matter. Essentia, Path Water, Open Water, and Boxed Water are US brands produced by purification rather than drawn from a named spring, so they belong to neither the spring nor the mineral category regardless of how they are presented. The distinction is not a judgment; it is simply what the labels legally mean.
The still, sparkling, and mineral waters discussed here are available by the case at Artisanal Aqua. Browse the full range of still water and sparkling water, chosen and described by hand.