Mineral water contains naturally occurring dissolved minerals, primarily calcium, magnesium, sodium, potassium, bicarbonate, sulfate, and chloride, all picked up as underground water filters through layers of rock. To legally carry the label “mineral water” in the United States, it must contain at least 250 parts per million (ppm) of total dissolved solids and come from a protected underground source. No minerals can be added afterward; everything in the bottle has to come from the earth itself.
The Major Minerals
The minerals present in the highest concentrations are calcium, magnesium, sodium, and bicarbonate. Their exact levels vary dramatically depending on the geology of the source. A calcium-rich mineral water might contain 500 to 600 mg of calcium per liter, while another brand from a different region might have less than 50 mg. The same is true for magnesium, which can range from trace amounts up to several hundred milligrams per liter.
Sulfate and bicarbonate are two other major dissolved compounds. Bicarbonate gives some mineral waters a slightly alkaline pH, typically falling in the 6.5 to 8.5 range. Sulfate contributes a faintly bitter or dry taste at higher concentrations. Potassium and silica round out the common mineral profile, though usually at lower levels than calcium or magnesium.
Trace Elements You Might Not Expect
Beyond the headline minerals, natural mineral water contains trace elements that reflect the specific geology it passed through. These include strontium, lithium, iodine, fluoride, and zinc. Concentrations are small, often measured in micrograms per liter rather than milligrams. Danish drinking water studies, for example, found lithium concentrations ranging from about 2.5 to 31 micrograms per liter and strontium from 0.07 to over 14 milligrams per liter, depending on location. Iodine levels ranged from barely detectable to 126 micrograms per liter.
These trace elements are considered essential or possibly essential for human health. Strontium plays a role in bone structure, iodine is critical for thyroid function, and lithium has long been studied for its effects on mood. The amounts in mineral water are far below therapeutic doses, but they do contribute to your overall dietary intake in small, consistent ways.
How It Differs From Other Bottled Water
The key distinction is the source and the rules about what can be done to it. Regular purified or spring water can be filtered, treated, and adjusted. Mineral water, by contrast, must originate from a geologically protected underground source, and its mineral content must remain consistent over time. Federal regulations prohibit adding minerals to the water after it’s collected.
Labeling rules also give you a rough guide to mineral density. If a mineral water has fewer than 500 ppm of dissolved solids, the label must say “low mineral content.” If it exceeds 1,500 ppm, the label must say “high mineral content.” Anything between 500 and 1,500 ppm needs no extra qualifier. Checking the nutrition label on the back will give you exact calcium, magnesium, and sodium numbers per serving, which is the fastest way to compare brands.
Your Body Actually Absorbs These Minerals
One reasonable question is whether the minerals dissolved in water are actually useful to your body, or just passing through. Research shows they’re absorbed quite well. In a study of healthy women, about 46% of the magnesium from mineral water was absorbed when the water was consumed on its own. That number climbed to roughly 52% when the water was drunk with a meal, a 14% relative increase. Those absorption rates are comparable to what you’d get from food sources.
Calcium from mineral water is similarly bioavailable. A study comparing calcium-rich mineral water (about 596 mg per liter) to a standard calcium supplement found that both effectively raised blood calcium levels and suppressed parathyroid hormone, a signal that the body recognized and used the calcium. The mineral water actually produced a more sustained effect over the course of the day because it was consumed in divided doses rather than all at once. Markers of bone breakdown dropped significantly with both the water and the supplement, but the water’s effect lasted longer into the afternoon and evening.
What Carbonation Adds (and Changes)
Many mineral waters are naturally sparkling, meaning carbon dioxide gas is present at the underground source. Others have carbonation added after collection. The CO2 dissolves in water to form carbonic acid, which lowers the pH slightly and gives the water its fizz and tangy bite. Sparkling mineral water is mildly acidic compared to still mineral water, but far less acidic than soft drinks or fruit juice. The mineral content itself remains the same whether the water is still or sparkling.
Effects on Digestion
Mineral waters high in bicarbonate and sulfate have a long history of use in European digestive therapy. Clinical research has started to explain why. Bicarbonate-sulfate-calcium-magnesium water has been shown to stimulate the release of cholecystokinin, a hormone that triggers the gallbladder to contract and empty bile into the digestive tract. This can improve fat digestion and reduce the heavy, bloated feeling some people experience after meals.
In a six-month study of patients with fatty liver, regular consumption of this type of mineral water increased levels of GLP-1 and PYY, two gut hormones involved in appetite regulation and blood sugar control. When the patients stopped drinking the water during a washout period, those hormone levels shifted back toward their original values, suggesting the mineral water was directly responsible for the changes. These effects are specific to waters with a particular mineral profile, not all mineral water.
How Mineral Content Varies by Brand
Because mineral water reflects its geological source, no two brands are identical. A French mineral water from volcanic rock will have a completely different profile than an Italian water from limestone or a German water from sandstone. Some practical differences worth noting:
- High-calcium waters (400+ mg/L) can deliver a meaningful share of your daily calcium needs from just a liter of water, useful if you’re lactose intolerant or don’t eat dairy.
- High-magnesium waters (100+ mg/L) can help close the gap on magnesium intake, which many people fall short on.
- High-sodium waters (200+ mg/L) may not be ideal if you’re watching your sodium intake for blood pressure reasons.
- Low-mineral waters (under 500 ppm TDS) have a lighter, more neutral taste and contribute fewer minerals overall.
The nutrition facts panel on the bottle is the most reliable way to know exactly what you’re getting. Look at calcium, magnesium, sodium, and bicarbonate to get the clearest picture of what’s dissolved in your particular bottle.