Most people choose bottled water for convenience or taste. Some choose it because their tap water is hard, or because they do not trust what is in the pipes. A smaller number choose it deliberately: for brewing, for coffee, for baking. But bottled water is also, obviously, drinking water. And the minerals in it affect your body in ways that are worth understanding, even if they rarely make the label.
This guide covers the same six ions that The Water Dictionary tracks across its bottled water database: calcium (Ca), magnesium (Mg), sodium (Na), sulphate (SO₄), chloride (Cl), and bicarbonate (HCO₃). For each one, we explain what it does to the taste, what it does in the body, and what range you will find across common bottled waters. This is not medical advice: if you are managing a specific condition, talk to your doctor. But for most people, the headline is reassuring. Bottled water is safe, and the minerals in it are either neutral or mildly beneficial.
How much mineral intake comes from water?
Less than you might think, but more than zero. For most people in most countries, food is the dominant source of calcium, magnesium, and sodium. Water is a secondary source. But "secondary" does not mean "negligible". If you drink two litres of water a day (a common recommendation), and that water contains 80 mg/L of calcium, you are getting 160 mg of calcium from water alone. The EU recommended daily intake for calcium is 800 mg. That is 20% of your daily requirement from water, without eating anything.
For magnesium, the arithmetic is similar. A water with 25 mg/L of magnesium delivers 50 mg per day from two litres. The EU RDI for magnesium is 375 mg. That is 13%. Not transformative, but not nothing.
The reason this matters for bottled water specifically is that the mineral content varies enormously. Volvic has about 12 mg/L of calcium. Contrex has 468 mg/L. That is a 39-fold difference between two waters you can buy in the same supermarket. If you are drinking bottled water every day, the one you choose affects your mineral intake whether you think about it or not.
Calcium
What it does to taste: At low concentrations (under 100 mg/L), calcium is largely tasteless. Above that, it can give water a slightly chalky or mineral quality. Very high calcium waters (above 300 mg/L) taste distinctly mineral and can feel heavy on the palate.
In the body: Calcium is the most abundant mineral in the human body. Most of it is in bones and teeth (about 99%), but the remaining 1% is critical for muscle contraction, nerve signalling, blood clotting, and enzyme function. There is consistent observational evidence linking calcium in drinking water to cardiovascular benefit, and the calcium in mineral water is well absorbed (comparable to dairy). At the concentrations found in bottled water, calcium is entirely safe and potentially useful, particularly if your diet is low in dairy.
Bottled water range: From near-zero (Highland Spring at 39 mg/L, Volvic at 12 mg/L) to extremely high (Contrex at 468 mg/L, Gerolsteiner at 348 mg/L). If you are choosing a daily drinking water and want a meaningful calcium contribution, look for waters in the 80–150 mg/L range.
Magnesium
What it does to taste: Magnesium has a more noticeable taste than calcium. At moderate concentrations (20–40 mg/L), it adds a subtle mineral brightness. Above 50 mg/L, it can introduce a bitter, slightly astringent edge. Very high magnesium waters (above 100 mg/L) taste distinctly bitter and are not to everyone's liking.
In the body: Magnesium is involved in over 300 enzymatic reactions, supporting muscle and nerve function, blood sugar regulation, bone development, and energy production. Deficiency is more common than most people realise: a significant portion of the population in developed countries does not meet the recommended daily intake through diet alone. Drinking water can be a useful supplementary source, particularly mineral-rich waters in the 20–50 mg/L range.
Bottled water range: Volvic has about 8 mg/L. Gerolsteiner has 108 mg/L. Donat Mg (a Slovenian therapeutic water) has over 1,000 mg/L, but that is sold as a health product rather than everyday drinking water. For a daily drinker, 20–50 mg/L is a reasonable range that balances palatability with a useful dietary top-up.
Sodium
What it does to taste: At low concentrations (under 20 mg/L), sodium is not perceptible. Between 20 and 100 mg/L, it adds a subtle sense of body or roundness that most people find pleasant without identifying as salty. Above 200 mg/L, water begins to taste noticeably salty. Above 400 mg/L, most people find it unpleasant.
In the body: Sodium regulates fluid balance and nerve impulse transmission. Most people get far more sodium from food than from water, and the vast majority of bottled waters contain less than 20 mg/L, contributing under 2% of the WHO's recommended daily limit of 2,000 mg. The only bottled waters worth noting are a handful of high-sodium sparkling waters (Vichy Catalan at around 1,097 mg/L, for instance). If you are on a sodium-restricted diet, check the label on those; for everything else, sodium in bottled water is a non-issue.
Bottled water range: Most UK supermarket waters are well under 20 mg/L. Highland Spring is about 6 mg/L. Evian is about 7 mg/L. San Pellegrino is about 34 mg/L. The high-sodium waters (Vichy Catalan, Badoit) are the exceptions, and they tend to be consumed in smaller quantities as table waters rather than as daily hydration.
Sulphate
What it does to taste: Sulphate contributes a dry, slightly bitter, mineral finish. Brewers know this well: it is the ion that accentuates hop bitterness in beer. In drinking water, the effect is similar but less pronounced. Below 100 mg/L, most people will not notice it. Between 100 and 250 mg/L, a dryness on the finish becomes detectable. Above 250 mg/L, the water tastes distinctly mineral and bitter.
In the body: Sulphate plays a role in amino acid synthesis and liver detoxification, but deficiency is essentially unheard of because the body produces it from dietary protein. At the concentrations found in most bottled waters (under 50 mg/L), sulphate is a non-issue. A small number of high-sulphate waters (Contrex, Hépar) can have a mild laxative effect above 500 mg/L, particularly when you first start drinking them. The effect is temporary and most people acclimatise within a few weeks.
Bottled water range: Most common bottled waters are under 30 mg/L of sulphate. Gerolsteiner is around 38 mg/L. Higher-sulphate waters like Contrex (1,187 mg/L) and Hépar (1,530 mg/L) are sold partly on their mineral content as a feature, and they taste accordingly.
Chloride
What it does to taste: Chloride at low concentrations (under 50 mg/L) is essentially tasteless. At moderate concentrations (50–150 mg/L), it adds a slight sweetness or smoothness to the mouthfeel, which brewers exploit in malt-forward beer styles. Above 250 mg/L, it contributes to a salty taste, working in combination with sodium. The sodium-to-chloride ratio matters more for taste perception than either ion alone.
In the body: Chloride works alongside sodium to maintain fluid balance and is a component of stomach acid. At the concentrations found in bottled water, it has no health significance. The WHO's guideline of 250 mg/L is based on taste, not health, and very few bottled waters come anywhere near it.
Bottled water range: Most bottled waters are well under 30 mg/L. San Pellegrino is about 52 mg/L. Very few bottled waters have problematic chloride levels.
Bicarbonate
What it does to taste: Bicarbonate is one of the most influential ions for the taste of water. At low concentrations (under 100 mg/L), water tastes clean and neutral. At moderate concentrations (100–300 mg/L), it adds a smooth, slightly alkaline character. Above 300 mg/L, water tastes distinctly mineral and can feel heavy or flat. Very high bicarbonate waters (above 1,000 mg/L, like Gerolsteiner at 1,817 mg/L or Vichy Catalan at 2,081 mg/L) are the waters that people describe as tasting "of minerals". Whether that is pleasant or not is entirely personal.
In the body: Bicarbonate is the body's primary pH buffer, maintaining blood acid-base balance within a narrow range. The body produces it endogenously, so drinking water is not a necessary source. That said, there is some evidence that very high-bicarbonate waters (above 600 mg/L) can help with acid reflux and dyspepsia by neutralising stomach acid. For everyday drinking at typical concentrations (50–300 mg/L), the health effect is negligible: your body regulates blood pH tightly regardless of what you drink.
Bottled water range: Enormous variation. Volvic has about 74 mg/L. Evian has about 360 mg/L. Gerolsteiner has 1,817 mg/L. If you find that a water tastes flat or heavy, bicarbonate is probably the reason.
Choosing a bottled water for health
The honest answer is that for most healthy adults, the mineral content of bottled water is a secondary concern. Your diet provides the majority of your mineral intake. The differences between bottled waters are real but unlikely to be transformative unless you are drinking large volumes of a very mineral-rich or very mineral-poor water.
That said, if you are choosing a daily drinking water and you care about the minerals, here are some practical guidelines.
If you want a meaningful calcium and magnesium contribution (because your diet is low in dairy, or you are concerned about bone density, or you are interested in getting minerals from every source available), look for waters with calcium above 80 mg/L and magnesium above 20 mg/L. San Pellegrino, Gerolsteiner, and Contrex all fit. The calcium in mineral water is bioavailable: studies show it is absorbed at least as well as calcium from dairy.
If you are watching your sodium (managing hypertension, on a restricted diet), check the label. Most waters are fine. Avoid Vichy Catalan, Badoit, and other high-sodium sparkling waters as daily drinkers. For occasional consumption, they are not a concern.
If you find certain waters upset your stomach, check the sulphate content. Waters above 500 mg/L of sulphate can have a laxative effect, especially when you first start drinking them. Contrex and Hépar are in this category.
If you experience acid reflux and are curious about mineral water as a partial remedy, bicarbonate-rich waters (above 600 mg/L HCO₃) have some evidence behind them. Gerolsteiner and Vichy Catalan are both high-bicarbonate. This is not a substitute for medical treatment, but some people find it helps.
If you prefer a clean, neutral taste for everyday drinking, look for waters with TDS under 200 mg/L. Volvic, Highland Spring, and most own-brand UK supermarket waters fit this category.
What the label tells you (and what it does not)
EU regulations require bottled natural mineral water to list the "characteristic composition" on the label, which includes the major ions. This is the best data you will get without sending the water to a laboratory. Most UK supermarket waters comply, though the quality of the information varies. Some give you all six ions. Some give you four. Some give you TDS and hardness but not the individual ions.
The most commonly omitted ion on labels is bicarbonate. This is frustrating, because bicarbonate is one of the most influential ions for both taste and health, and it is the hardest to find from any source. When The Water Dictionary lists bicarbonate for a bottled water, it is often because we have sourced it from the manufacturer's technical data sheet rather than the retail label.
The other thing labels do not tell you is how the mineral content compares to other waters. A label might say "calcium: 78 mg/L" and you have no frame of reference for whether that is high, low, or average. This is where The Water Dictionary's database is useful: it puts every water on the same scale, so you can see at a glance how one compares to another.
A note on "mineral water" versus "spring water"
These terms have legal definitions in the EU and UK, and they are not interchangeable. "Natural mineral water" must come from an officially recognised source with a stable mineral composition, and it must be bottled at the source. "Spring water" must come from an underground source and be bottled at the source, but it does not need to have a stable composition and is subject to fewer regulations. Both can be perfectly good drinking water. The distinction matters mainly for consistency: if you are choosing a water for its mineral profile, natural mineral water guarantees that the profile will be the same every time you buy it. Spring water may vary between batches.
Summary
Water is not a supplement. It is not medicine. It is the thing you drink the most of, every day, for your entire life. The minerals in it contribute to your intake of calcium, magnesium, sodium, and other ions in amounts that range from trivial (for low-mineral waters) to meaningful (for high-mineral waters). The choice of which bottled water to drink is usually made on taste and convenience, and that is fine. But if you are already paying attention to what is in your water (and if you are reading The Water Dictionary, you probably are), the health dimension is worth understanding too.
None of this needs to be complicated. Bottled water is safe. The minerals in it are, at worst, irrelevant to your health and, at best, a useful dietary top-up. Choosing a water you enjoy drinking is the single best thing you can do, because the water you drink the most of is the one that matters.