Which water is richest in magnesium? The full ranking (mg/L)
The short answer
Hydroxydase (240 mg/L) and Rozana (160 mg/L) are the French mineral waters richest in magnesium, ahead of Hépar (119 mg/L), according to values taken from Anses’s Ciqual 2025 table. One litre of Rozana covers 53% of the adequate intake of an adult woman, set at 300 mg a day. No water sold in France reaches the legal threshold that would allow source of magnesium to be written on a label.
Ranking of mineral waters by magnesium content
The values below come from the Ciqual 2025 table, which publishes the mineral composition of sixty named waters. Ciqual expresses them in mg per 100 g; they are converted here into mg per litre, the unit used on labels. Sodium is in the table because it completely changes how useful a water is: several of the most magnesium-rich are also very salty.
| Water | Magnesium (mg/L) | Calcium (mg/L) | Sodium (mg/L) |
|---|---|---|---|
| Hydroxydase (sparkling) | 240 | 201 | 1,840 |
| Rozana (sparkling) | 160 | 301 | 493 |
| Hépar (still) | 119 | 549 | 14 |
| Didier (sparkling) | 113 | 137 | 126 |
| Apollinaris | 110 | 90 | 380 |
| Didier (still) | 107 | 172 | 130 |
| St-Michel-de-Mourcairol (sparkling) | 100 | 230 | 175 |
| Parot (sparkling) | 94 | 110 | 1,010 |
| Ardesy (sparkling) | 92 | 170 | 650 |
| St-Antonin (still) | 89 | 568 | 8 |
| La Française (still) | 83 | 354 | 680 |
| Badoit (sparkling) | 80 | 153 | 180 |
| St-Diéry (sparkling) | 80 | 85 | 77 |
| Prince Noir (still) | 78 | 528 | 9 |
| Contrex (still) | 75 | 468 | 4 |
Hydroxydase is not a table water
It dominates the ranking, but it is sold in pharmacies in 20 cl ampoules, as a course, and it provides 1,840 mg of sodium per litre. On its own, a one-litre bottle would supply almost as much sodium as the daily salt ceiling set by Anses, which rules it out as an everyday drink. For daily use, the real ranking starts at Rozana.
Why the best-known waters are not in the table
Because they provide almost nothing. Vittel tops out at 42 mg/L, Evian at 26 mg/L, Volvic at 8 mg/L and Perrier at 4 mg/L. Tap water is around 10 mg/L according to Ciqual. Between a glass of Volvic and a glass of Rozana, the ratio is one to twenty. The choice of bottle therefore matters far more than the quantity drunk, a point developed in our guide to how much water to drink a day.
The word “magnesium-rich” is regulated, and the bar is lower than you might think
Annex III of European Directive 2009/54/EC allows the mention contains magnesium on a natural mineral water from 50 mg/L. That is a modest threshold: around fifteen waters clear it.
But the nutrition claim source of magnesium, which falls under Regulation 1924/2006, requires for a drink 7.5% of the nutrient reference value per 100 ml, which is 281 mg/L. No water sold in France gets there, not even Hydroxydase. A water can therefore be magnesium-rich without being allowed to call itself a source of magnesium: the distinction is legal, and it sums up the subject rather well. Water contributes, it does not cover your needs.
What a litre really covers
Anses sets adequate intakes, published on 21 February 2025. These are not vital minimums but population reference points.
Adult woman: 300 mg a day
One litre of Rozana provides 160, or 53%. A litre of Hépar, 40%. A litre of Contrex, 25%. A litre of Evian, less than 9%.
Adult man: 380 mg a day
The same waters cover 42%, 31% and 20% respectively. The gap between men and women is not trivial: with the same water, a man fills a fifth less of his reference intake.
Athletes: no specific reference intake
Anses does not publish a separate value for athletes. Losses through sweat exist but remain small compared with dietary intake, and the adequate intake is set per adult, not per kilo of body weight. What really changes during training is the volume you drink: three litres of a magnesium-rich water supply three times as much as one litre. Our guide to hydration and sports performance deals with volume and sodium losses, which are the real issue.
Pregnancy and breastfeeding: 300 mg, as for any adult woman
This is a point often misreported: Anses does not raise the adequate magnesium intake during pregnancy or breastfeeding. It stays at 300 mg a day. On the other hand, a very sodium-rich or very sulphate-rich water is hard to justify at that time, and a moderately mineralised still water such as Hépar or Prince Noir is a better compromise than Rozana or Parot.
Calculate your own coverage
Magnesium-rich water or a supplement: where is the tipping point
The magnesium in water is well absorbed
This is the solid part of the evidence. A bioavailability study carried out on ten men, using magnesium-28 isotope tracing, measured an average absorption of 59.1% from a magnesium-rich water (Verhas et al., European Journal of Clinical Nutrition, 2002, PMID 12001016). A second, crossover study in ten women using stable isotopes found 45.7% for water drunk on its own and 52.3% during a meal, a statistically clear difference (Sabatier et al., American Journal of Clinical Nutrition, 2002, PMID 11756061).
Two honest caveats: the numbers are small, ten people per study, and both studies were funded or run by players in the water industry, which the publications themselves state. The conclusion remains sound in its general direction (water is a usable source), but it does not justify a figure to the nearest tenth of a point.
The practical consequence is simple: drink your magnesium-rich water with meals rather than on an empty stomach.
The laxative effect comes from sulphates, not magnesium
This is the most widespread confusion on the subject. Hépar carries 1,530 mg of sulphates per litre according to its official composition, whereas the European sulphated mention applies from 200 mg/L. These sulphates are what speed up transit, and that is in fact the brand’s selling point. Its 119 mg of magnesium have almost nothing to do with it.
In other words: a water can be magnesium-rich without being laxative, and the reverse is also true. If you want magnesium without the effect on transit, a low-sulphate water such as Prince Noir or St-Antonin does the job.
When a supplement becomes more logical
Water has a built-in ceiling. Even drinking two litres of the most magnesium-rich table water, you take in 320 mg, the equivalent of one daily reference intake, and you have to drink two litres of that particular water, every day, without variety. As soon as the goal goes beyond covering the reference intake, for example in the case of a documented deficiency, a supplement is the only tool of the right size. Water remains the foundation, not the lever. The signs that should make you suspect a shortfall are detailed in our guide to the benefits and signs of magnesium deficiency.
The foods that provide more than a litre of water
Rankings of magnesium-rich foods put basil (711 mg/100 g) or dried mint (602 mg/100 g) at the top. That is accurate and useless: you eat two grams of them. The table below works in real portions, which changes the order of the ranking.
| Food | Portion | Magnesium provided | Share of the reference intake (300 mg) |
|---|---|---|---|
| Winkle | 100 g | 310 mg | 103% |
| Pumpkin seeds | 30 g | 178 mg | 59% |
| Whelk | 100 g | 144 mg | 48% |
| Brazil nuts | 30 g | 113 mg | 38% |
| Sunflower seeds | 30 g | 109 mg | 36% |
| Spinach | 200 g | 109 mg | 36% |
| Quinoa, cooked | 150 g | 107 mg | 36% |
| Chia seeds | 30 g | 101 mg | 34% |
| Tofu | 100 g | 100 mg | 33% |
| Almonds | 30 g | 81 mg | 27% |
| Buckwheat flour | 50 g | 79 mg | 26% |
| Cashew nuts | 30 g | 67 mg | 22% |
| Chickpeas, cooked | 150 g | 66 mg | 22% |
| Dark chocolate 70% | 30 g | 60 mg | 20% |
| Unsweetened cocoa | 10 g | 50 mg | 17% |
The result is clear: thirty grams of pumpkin seeds provide more than a litre of Rozana, and a plate of winkles covers a day’s reference intake on its own. Water is a handy top-up because you drink it without thinking; it is not the main lever. Stress, often cited to justify a course of supplements, is first dealt with through your plate: our guide to diet and stress management goes back over what the studies really support.
The full ranking of foods, family by family and sorted by intake per portion, is in our guide to magnesium-rich foods: winkles beat every water by a wide margin, with 310 mg per 100 g.
Magnesium-rich water and constipation: what the trials show
Hépar’s effect on transit is not just a selling point: it has been tested in double-blind controlled trials against a low-mineral water.
| Trial | Participants | Result |
|---|---|---|
| Hépar, 4 weeks, 2014 | 244 constipated women aged 18 to 60, followed by 62 GPs in France | At week 2, constipation reduced in 37.5% of women with 1 litre of Hépar a day, 30.9% with half a litre, against 21.1% with the low-mineral water; no effect in the first week |
| Hépar, 14 days, 2019 | 226 constipated patients | Treatment response in 50% with 1 litre of Hépar a day, against 29%; average time to response of 6.4 days against 7.3 |
| Another calcium-magnesium sulphate water, 6 weeks, 2016 | 100 constipated people | More frequent stools after 3 weeks, but no longer a significant difference at 6 weeks |
In the 2014 trial, the authors link patients’ response to the water’s magnesium sulphate concentration: it is the combination of sulphates and magnesium that works, and half a litre was not enough to do significantly better than the control water. Tolerance was judged very good in both Hépar trials. In practice, allow a litre a day and at least one to two weeks before judging. If constipation persists, or comes with pain, blood in the stools or weight loss, you need to see a doctor.
What about a baby’s bottle? Under French rules for bottled waters, recalled by Anses in 2022, a water can only carry a mention relating to infant feeding if it contains at most 10 mg of nitrates and 0.05 mg of nitrites per litre. To prepare a bottle, rely on that mention on the label rather than on the magnesium content.
Precautions
Kidney failure: ask for medical advice before changing your water. The kidney is the organ that regulates magnesium. When it works poorly, a high daily intake is no longer eliminated normally. This is the only truly serious contraindication on this subject.
High blood pressure: look at the sodium column, not the magnesium column. Parot provides 1,010 mg of sodium per litre and Rozana 493 mg. Two litres of Parot is already more than 2 g of sodium, to be compared with the 5 g of salt a day that Anses sets as a ceiling, bearing in mind that 5 g of salt corresponds to about 2 g of sodium. For a water that is both magnesium-rich and low in sodium, Hépar (14 mg/L), St-Antonin (8 mg/L) and Prince Noir (9 mg/L) are the only answers in the table.
Do not drink a litre of Hépar a day without thinking. Its 1,530 mg of sulphates have an effect on transit that is not trivial if you are not used to it. Build up gradually, or alternate with a more neutral water.
Variety remains the best rule. No water is good on every measure, and alternating two or three bottles avoids pushing one mineral at the expense of the others. The other composition reference points are in our drinks section.
And the other way round? See our guide too much magnesium: symptoms and maximum dose.
Frequently asked questions
Which water contains the most magnesium?
Hydroxydase, with 240 mg/L, but it is sold in pharmacies in ampoules and provides 1,840 mg of sodium per litre. Among table waters, it is Rozana with 160 mg/L, ahead of Hépar at 119 mg/L. The values come from the Ciqual 2025 table; the other magnesium-rich waters are listed in the drinks section.
How many litres do you need to drink to cover your magnesium needs?
With Rozana, 1.9 litres would cover the 300 mg of an adult woman and 2.4 litres the 380 mg of a man. That is not a realistic everyday strategy: it is better to combine a magnesium-rich water with nutrient-dense foods. The calculator above gives your real coverage, and our hydration calculator gives you the volume of water that suits you.
Is Hépar really a magnesium-rich water?
Yes, 119 mg/L puts it in third place and well above the 50 mg/L threshold that allows the mention contains magnesium. But its reputation comes mainly from its 1,530 mg of sulphates per litre, which act on transit, an effect separate from magnesium. It also has the advantage of being very low in sodium, 14 mg/L. See also the signs of magnesium deficiency.
Is Contrex a magnesium-rich water?
Moderately: 75 mg/L according to Ciqual, which is above the contains magnesium threshold but still half as much as Rozana. Its strong point is calcium, 468 mg/L. If your goal is magnesium, it is not the best choice; if it is calcium, that is another matter: see dairy products for comparison.
Can a magnesium-rich water replace a supplement?
To cover a daily reference intake, it makes a serious contribution: the magnesium in water is absorbed at about 59% (PMID 12001016). To correct an established deficiency, no: water tops out around 300 mg a day if you drink two litres, which leaves little margin. The reference points on deficiency help you place your own case.
Should you drink magnesium-rich water on an empty stomach or with meals?
With meals. Measured absorption goes from 45.7% to 52.3% when the water is drunk during a meal (PMID 11756061). The gap is modest but it goes in the right direction, and it costs nothing to apply. Our guide to how much water to drink a day details how to spread it across the day.
Does tap water provide magnesium?
Very little: about 10 mg/L according to Ciqual, or 3% of a woman’s reference intake for a litre. The content varies with local geology, but it remains an order of magnitude below magnesium-rich waters. For magnesium, your plate is a far more effective lever: see the food table above and the nuts and seeds section.
Does Hépar really work against constipation?
In two controlled trials, 1 litre of Hépar a day did better than a low-mineral water: 37.5% against 21.1% of women relieved at week 2 in 2014, and 50% against 29% of responders at 14 days in 2019. Half a litre a day did not do significantly better.
How long does a magnesium-rich water take to act on transit?
In the Hépar trials, no effect appeared in the first week; the average time to response was about 6 days, with one litre a day.
Can you prepare a baby’s bottle with a magnesium-rich water?
Choose a water that carries the mention of suitability for infant feeding: among other things, it requires at most 10 mg of nitrates per litre. Ask your paediatrician for advice.
Our sources
- Ciqual 2025 table, Anses: mineral composition of bottled waters (rows 76000 to 76103), converted from mg/100 g to mg/L.
- Anses, Nutritional reference values for vitamins and minerals (in French), published 21 February 2025: adequate magnesium intakes.
- Directive 2009/54/EC, Annex III: contains magnesium mention from 50 mg/L; Regulation 1924/2006: source of claim at 7.5% of the NRV per 100 ml for a drink.
- Verhas M. et al., Magnesium bioavailability from mineral water. A study in adult men, European Journal of Clinical Nutrition, 2002: PMID 12001016.
- Sabatier M. et al., Meal effect on magnesium bioavailability from mineral water in healthy women, American Journal of Clinical Nutrition, 2002: PMID 11756061.
- Official composition of Hépar water: sulphate content.
- Dupont C, Campagne A, Constant F. Efficacy and safety of a magnesium sulfate-rich natural mineral water for patients with functional constipation. Clin Gastroenterol Hepatol, 2014 (PMID 24342746).
- Dupont C et al. Time to treatment response of a magnesium- and sulphate-rich natural mineral water in functional constipation. Nutrition, 2019 (PMID 31170680).
- Naumann J et al. Effects of sulfate-rich mineral water on functional constipation: a double-blind, randomized, placebo-controlled study. Forsch Komplementmed, 2016 (PMID 27924798).
- Anses. Risk assessment of nitrate and nitrite consumption (in French), collective expert report (referral 2020-SA-0106), 2022: order of 14 March 2007, limits for the mention relating to infant feeding.
