The healthiest bottled water is one that contains naturally occurring minerals, particularly calcium and magnesium, and has been stored properly. Mineral water and spring water from reputable sources consistently come out ahead of purified or distilled options because they deliver trace nutrients your body actually uses. But the full picture involves more than just what’s in the water. How it’s packaged, how it’s stored, and what contaminants it’s been tested for all matter.
Mineral Water vs. Spring Water vs. Purified Water
The FDA defines three main categories of bottled water, and the differences are more than marketing. Mineral water comes from an underground source and must contain at least 250 parts per million of total dissolved solids. Those minerals and trace elements have to come naturally from the source and can’t be added afterward. Spring water is collected from an underground formation where water flows naturally to the surface, and it must maintain the same composition as what comes out of the ground on its own. Purified water has been processed through distillation, reverse osmosis, or similar methods that strip out most dissolved substances.
That last category is where things get tricky. Purified water is clean, but “clean” isn’t the same as “healthy.” The World Health Organization has flagged several concerns with drinking demineralized water long term: it can increase urine output in ways that throw off your electrolyte balance, and it may alter the body’s metabolic function. It also tastes flat, which sounds minor but often leads people to drink less water overall.
Why Minerals in Water Matter
Epidemiological research from the U.S., Europe, and Russia suggests that drinking water with at least 20 to 30 mg/L of calcium and 10 mg/L of magnesium is associated with cardiovascular health benefits. These aren’t large amounts compared to what you’d get from food, but water is something you consume every day in significant volume, so even modest mineral concentrations add up.
Not all bottled waters deliver the same mineral load. Total dissolved solids (TDS) is the simplest way to compare. Fiji water sits at around 210 mg/L. Evian comes in at 357 mg/L. San Pellegrino jumps to 1,109 mg/L, and Gerolsteiner, a German mineral water, reaches 2,527 mg/L. Higher TDS generally means more calcium, magnesium, and bicarbonate, though the exact mineral profile varies by source. If you’re choosing bottled water partly for its mineral content, check the label for calcium and magnesium specifically rather than relying on TDS alone.
The Alkaline Water Question
Alkaline water, typically with a pH between 8 and 9.5, is marketed as a health upgrade. The theory is that it neutralizes acid in the body, potentially protecting against disease. The reality is far less dramatic. Some evidence suggests alkaline water may help with acid reflux, particularly when paired with a plant-based Mediterranean diet. There are also preliminary findings that it could slow bone loss, though researchers aren’t sure whether the effect comes from the higher pH or simply the added calcium these products often contain.
Claims about cancer prevention and stroke reduction remain unproven. And alkaline water with a pH above 9.8 carries real safety concerns, including elevated potassium levels in the blood. That’s especially dangerous for anyone with kidney disease. For most people, alkaline water isn’t harmful, but it’s also not the superfood its branding suggests.
Contaminants Worth Knowing About
Bottled water is regulated by the FDA, and recent testing for PFAS (sometimes called “forever chemicals”) found that while 10 out of the samples tested had detectable levels, none exceeded the maximum contaminant levels set by the EPA for public drinking water. The FDA screened for 18 types of PFAS across those samples. That’s reassuring, though it’s worth noting that the EPA has only established limits for six types of PFAS so far, and two of the chemicals detected in bottled water don’t yet have formal safety thresholds.
The FDA has the authority to act against any bottled water that presents a safety concern, even without a formal standard for a specific contaminant. Still, if PFAS exposure is something you want to minimize, choosing brands that publish independent third-party testing results gives you more visibility into what you’re drinking.
Plastic Packaging and Storage Conditions
Most bottled water comes in PET plastic, and those bottles can leach a metal called antimony into the water. Under normal conditions, the amounts are tiny. But temperature changes everything. Research published in the journal Environmental Science & Technology found that when PET bottles were stored at 140°F (60°C) for seven days, antimony concentrations increased by 1.1 to nearly 11 times compared to pre-storage levels. Temperature was the dominant factor, far more influential than how long the bottle sat on a shelf.
In practical terms, this means a bottle of water left in a hot car or stored in a warm garage is a very different product from one kept at room temperature. If you’re buying bottled water in bulk, store it somewhere cool and out of direct sunlight. Glass bottles eliminate this concern entirely, though they’re heavier and more expensive.
Microplastics are the other packaging concern. Research from Ohio State University found that bottled water contained roughly three times as many nanoplastic particles as treated tap water, and over half of those particles came directly from the packaging itself. The long-term health effects of ingesting nanoplastics are still being studied, but if reducing exposure is a priority, glass-bottled mineral water is the cleanest option available.
What to Look for on the Label
A few quick things to check when comparing brands:
- Source type: Mineral water or spring water will retain naturally occurring minerals. Purified water won’t, unless minerals are added back.
- Calcium and magnesium levels: Look for at least 20 mg/L calcium and 10 mg/L magnesium to hit the threshold associated with health benefits.
- TDS: A reading above 250 mg/L means the water qualifies as mineral water under FDA rules and will have a more complex mineral profile.
- Packaging: Glass is ideal for minimizing microplastic and chemical leaching. If you’re buying PET plastic, store it cool.
- Third-party testing: Brands that voluntarily test for PFAS and heavy metals, and publish those results, are offering a level of transparency the FDA doesn’t require.
European mineral waters like Gerolsteiner, San Pellegrino, and Evian tend to score well on mineral content because EU regulations for natural mineral water are strict about source protection and mineral consistency. In the U.S., brands like Mountain Valley Spring Water (sold in glass) and Fiji (high TDS from volcanic rock filtration) are popular choices among people prioritizing mineral content and packaging quality. Ultimately, the healthiest bottled water is one you’ll actually drink enough of, that delivers useful minerals, and that hasn’t been compromised by heat or questionable packaging.