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Gerolsteiner Sprudel
Gerolsteiner Sprudel from Gerolstein, Eifel volcanic region — 348 mg calcium, 108 mg magnesium, 118 mg sodium per litre. Hardness, what a litre contributes against the EFSA reference intakes, and the EU label claims the analysis supports.
Where it comes from
The Eifel is old volcanic country, and carbon dioxide seeping up through the dolomite there dissolves calcium and magnesium in a way ordinary groundwater cannot. Gerolsteiner is the result and the German benchmark for a mineral-rich sparkling water: 348 mg of calcium and 108 mg of magnesium in a litre, held in solution by 1 816 mg of bicarbonate. Sodium at 118 mg is moderate rather than low, which is the trade-off for the calcium and magnesium.
Source: Gerolstein, Eifel volcanic region · Category: Natural mineral water · Carbonation: Naturally carbonated
This is a reference table, not a diagnosis and not a prescription. If a clinician has put you on a sodium, calcium, potassium or fluid restriction, that number comes from them and overrides anything here. Analyses are revised as sources are re-tested, so the label on the bottle you are holding always outranks this page.
The published analysis
| Constituent | mg per litre | What a litre of it means |
|---|---|---|
| Calcium | 348 | 36.6% of the 950 mg calcium reference |
| Magnesium | 108 | 30.9% of the 350 mg magnesium adequate intake |
| Sodium | 118 | 5.9% of the 2.0 g sodium intake · 0.3 g as salt |
| Potassium | 11 | |
| Bicarbonate | 1 816 | |
| Sulphate | 38 | |
| Chloride | 40 | |
| Fluoride | 0.2 | below the 1.5 mg/l infant labelling threshold |
| Dry residue at 180 °C | 2 527 | the figure EU law uses for the mineral-content claims |
How hard it is
Hardness is nothing but the calcium and magnesium already in the table above, re-expressed as though all of it were calcium carbonate. For Gerolsteiner Sprudel the arithmetic runs 348 ÷ 40.08 + 108 ÷ 24.31 = 13.13 mmol per litre.
| Unit | Value | Where you meet it |
|---|---|---|
| Millimoles per litre | 13.13 | the chemistry, and the German consumer bands |
| German degrees °dH | 73.6 | dishwasher and washing-machine settings in the Nordics and Baltics |
| French degrees °fH | 131.4 | French and Belgian labelling |
| mg per litre as CaCO₃ | 1 313.8 | the international classification and most water-utility reports |
That places it at very hard on the classification used in the international drinking-water literature, and hart (hard) on the three-band German scale printed on detergent packets. Hardness has no health-based guideline value; what it changes is limescale, soap and the taste. More on hardness.
What EU labelling law lets this water claim
Annex III of Directive 2009/54/EC fixes exactly which indications a natural mineral water may print and the figure each one requires. Applying those rules to the analysis above:
| Indication | Criterion | This water |
|---|---|---|
| “Very low mineral content” | not above 50 mg/l dry residue | does not qualify |
| “Low mineral content” | not above 500 mg/l dry residue | does not qualify |
| “Rich in mineral salts” | above 1 500 mg/l dry residue | qualifies |
| “Contains bicarbonate” | above 600 mg/l bicarbonate | qualifies |
| “Contains sulphate” | above 200 mg/l sulphate | does not qualify |
| “Contains chloride” | above 200 mg/l chloride | does not qualify |
| “Contains calcium” | above 150 mg/l calcium | qualifies |
| “Contains magnesium” | above 50 mg/l magnesium | qualifies |
| “Contains fluoride” | above 1 mg/l fluoride | does not qualify |
| “Contains sodium” | above 200 mg/l sodium | does not qualify |
| “Suitable for a low-sodium diet” | below 20 mg/l sodium | does not qualify |
A litre against a day
| Nutrient | Per litre | Share of an adult day |
|---|---|---|
| Calcium | 348 mg | 36.6% of the 950 mg EFSA reference intake |
| Magnesium | 108 mg | 30.9% of the 350 mg adequate intake for men |
| Sodium | 118 mg | 5.9% of the 2.0 g safe and adequate intake |
The sodium contribution is small enough to disappear into the noise of an ordinary diet, where bread and cheese do the real work. Which is the general rule for bottled water and sodium — the exceptions are the sodium-bicarbonate waters, and they announce themselves on the label.
Analyses: the figures each producer publishes on the label or in its technical sheet — see the basis line on every water page. Reference intakes: EFSA Dietary Reference Values. Label claims: Directive 2009/54/EC, Annex III. Mineral-water constituent limits and the fluoride labelling rule: Directive 2003/40/EC. Tap-water parametric values: Directive (EU) 2020/2184. Checked 2026-09-06.
Frequently asked questions
What is in Gerolsteiner Sprudel?
Gerolsteiner Sprudel is naturally carbonated from Gerolstein, Eifel volcanic region, natural mineral water. The published analysis is 348 mg calcium, 108 mg magnesium, 118 mg sodium per litre.
Is Gerolsteiner Sprudel hard water?
Calcium and magnesium together come to 13.13 mmol per litre, which is 73.6 °dH or about 1 313.8 mg per litre as calcium carbonate — very hard on the international scale and hart (hard) on the German one.
Is Gerolsteiner Sprudel suitable for a low-sodium diet?
Not on the EU criterion, which reserves that claim for waters under 20 mg of sodium per litre. This one carries 118 mg per litre, so a litre is roughly 5.9% of the 2.0 g safe and adequate sodium intake before any food is counted.
How much magnesium does Gerolsteiner Sprudel have?
108 mg per litre, which is about 30.9% of the EFSA adequate intake of 350 mg a day for adult men and 36% of the 300 mg figure for women. EU labelling allows a "contains magnesium" claim above 50 mg per litre.
Waters with a similar mineral load
Hepar
France · Still
Narzan
Russia · Naturally carbonated
Contrex
France · Still
Vichy Catalan
Spain · Naturally carbonated
All waters compared
The full table, grouped by mineral content.
Water hardness explained
Degrees, millimoles and parts per million, converted.
Know what you drank, not just what you bought
TempoLife logs hydration alongside food and sleep, so the litre you actually drank is in the same picture as everything else.