Thonon
Thonon is a natural mineral water from the Versoie spring in Thonon-les-Bains, a spa town on the French shore of Lake Geneva in Haute-Savoie. Water follows a long underground path through glacial moraines and Alpine limestone before emerging at the Versoie source. The use of the Thonon spring is documented from the Gallo-Roman period; the French Academy of Medicine formally recognised the water as being of public health interest in 1890. The brand is operated by Sources ALMA.
Mineral composition
| mg/L | |
|---|---|
| Calcium | 92 |
| Magnesium | 16 |
| Sodium | 6 |
| Sulfate | 12 |
| Chloride | 14 |
| Bicarbonate | 340 |
Compositions can vary by season and source. Read our methodology.
Mineral character
Calcium is 92 mg/L, magnesium 16 mg/L, sodium 6 mg/L, sulphate 12 mg/L, chloride 14 mg/L, and bicarbonate 340 mg/L. Hardness is 296 mg/L as CaCO₃. Bicarbonate is the dominant ion and calcium is the principal cation. Sodium and sulphate are low for a water of this hardness, consistent with filtration through glacial moraine and limestone with limited evaporite contact.
Documented use and context
The French Academy of Medicine declared Thonon water to be of public health interest in June 1890, based on observed diuretic properties. This is a documented attribution in the French historical medical record. The 19th-century Academy’s procedures differ from modern systematic review and the declaration does not constitute a clinical evidence base.
Use-case suitability
- CoffeeNot used in any current coffee recipe. Hardness 296 mg/L is above the 9–266 mg/L range of these targets.
- TeaNot used in any current tea recipe. Hardness 296 mg/L is above the 37–59 mg/L range of these targets.
- BrewingAppears in blends for Vienna.
- BakingAppears in blends for Montreal Bagel.
- AquariumNot used in any current aquarium recipe. Hardness 296 mg/L is above the 35–212 mg/L range of these targets.
- HorticultureNot used in any current horticulture recipe. Hardness 296 mg/L is above the 12–54 mg/L range of these targets.
Used in these recipes
Where to buy
FR
Carrefour, Leclerc, Auchan, Intermarché
€0.50-0.70 per litre
Available through French supermarkets including Carrefour, Leclerc, Auchan, and Intermarché. Not widely available in the UK. As of March 2026.