For most people, filtered tap water strikes the best balance of safety, mineral content, and cost. It retains beneficial minerals like calcium and magnesium while removing common contaminants, and it undergoes more frequent testing than bottled alternatives. But the full answer depends on what’s in your local supply, how you filter it, and what you’re optimizing for.
Why Minerals in Water Matter
Water isn’t just hydration. It can be a meaningful source of calcium and magnesium, two minerals most people don’t get enough of. North American tap water from groundwater sources averages about 52 mg/L of calcium and 20 mg/L of magnesium. Drinking two liters a day from a typical tap source can cover 8% to 16% of your daily calcium needs and 6% to 31% of your magnesium needs.
That might sound modest, but it adds up over a lifetime. Research has consistently linked water that’s higher in these minerals (often called “hard” water) with a somewhat lower risk of cardiovascular disease, with magnesium likely driving most of that benefit. On the flip side, long-term consumption of demineralized water has been associated with higher fracture risk in children, certain pregnancy complications, and some neurodegenerative conditions. Cooking with demineralized water makes this worse: it leaches up to 60% of the calcium and magnesium out of vegetables, meat, and grains during preparation.
Tap Water: Affordable and Well Regulated
Municipal tap water in the United States falls under EPA oversight through the Safe Drinking Water Act of 1974. Utilities must test frequently and report results publicly. The EPA sets limits for over 90 contaminants, and your local water utility is required to send you an annual quality report (sometimes called a Consumer Confidence Report) detailing exactly what’s in your supply.
The main vulnerabilities of tap water happen after it leaves the treatment plant. Lead can leach from older pipes and fixtures on the way to your faucet, which is why the EPA allows up to 15 parts per billion of lead in tap water (compared to just 5 ppb for bottled water, which never touches lead pipes). Chlorine byproducts can also form during treatment. If your home was built before 1986 or your city has known infrastructure issues, a point-of-use filter addresses both of these problems cheaply.
Fluoride is another consideration. Most U.S. municipal systems add fluoride at 0.7 mg/L, a level the U.S. Public Health Service recommends for preventing tooth decay while minimizing dental fluorosis. If you prefer to avoid added fluoride, you’ll need a filter specifically rated to remove it, since standard carbon filters don’t.
Bottled Water: Convenient but Not Superior
The FDA regulates bottled water and generally adopts the same contaminant limits the EPA sets for tap water. But bottled water plants aren’t required to test as frequently as municipal systems, and results aren’t made public in the same way. In practice, much of what’s sold as “purified” bottled water is simply processed municipal water with minerals stripped out.
The bigger concern is plastic. A 2024 study highlighted by the National Institutes of Health found that a single liter of bottled water contained an average of 240,000 tiny plastic particles. These are nanoplastics small enough to cross cell membranes, and their long-term health effects are still being studied. If you do buy bottled water, glass bottles sidestep this issue entirely.
North American spring waters, despite their premium branding, often contain less calcium and magnesium than ordinary tap water. The median calcium content of North American spring water is just 6 mg/L, compared to 36 mg/L in surface-sourced tap water. European mineral waters are a different story. Moderately mineralized European brands average 262 mg/L of calcium and 64 mg/L of magnesium, enough to supply 20% to 58% of your daily calcium from just one liter.
Filtered Water: The Middle Ground
A basic carbon filter (the kind in most pitcher filters and faucet attachments) removes chlorine, some pesticides, and lead while leaving minerals intact. For most municipal water supplies, this is all you need. It improves taste without stripping out the calcium and magnesium your body benefits from.
Reverse osmosis systems go much further, removing 94% to 98% of calcium and magnesium along with 95% of fluoride, 90% of nitrates, and nearly all lead and heavy metals. That thoroughness is valuable if your water source is contaminated with industrial chemicals or heavy metals, but for clean municipal water, it creates the same mineral-depleted profile as distilled water. Some RO systems include a remineralization stage that adds calcium and magnesium back in. If you use RO at home, that add-on is worth the small extra cost.
Distilled and Purified Water
Distilled water is boiled into steam and condensed back into liquid, leaving virtually all minerals and contaminants behind. Purified water is a broader category that includes distillation, deionization, and reverse osmosis. Both produce very low Total Dissolved Solids (TDS) readings, often under 10 mg/L.
The World Health Organization rates water with TDS below 300 mg/L as “excellent” tasting, and water below 1,000 mg/L as generally acceptable. But the WHO doesn’t set a minimum TDS for health, which leaves a gap: water can taste perfectly fine and still be too mineral-poor for long-term use as your only drinking source. The cooking losses are especially relevant here. If you use distilled or RO water for everything, including boiling pasta, making soup, and steaming vegetables, you’re losing a significant share of the minerals in your food before you eat it.
Alkaline and Specialty Waters
Alkaline water typically has a pH between 8 and 9.5, compared to tap water’s usual range of 6.5 to 8.5. Some mineral waters are naturally alkaline because of the rock they flow through. Others are artificially adjusted with added minerals or electrolysis. Your body tightly regulates blood pH regardless of what you drink, so the pH of your water doesn’t meaningfully change your body’s acid-base balance. Some people find alkaline water easier on the stomach, but there’s no strong evidence it prevents disease or improves hydration beyond what regular water does.
Hydrogen water, electrolyte-enhanced water, and other specialty products carry price tags that far exceed any demonstrated benefit for healthy people. If you exercise intensely or sweat heavily, adding a pinch of salt and a squeeze of citrus to regular water replaces the same electrolytes at a fraction of the cost.
Choosing What Works for You
Start with your local water quality report. If your municipal water meets EPA standards and your home plumbing is in good shape, a simple carbon filter is the most cost-effective upgrade. It removes the things most likely to affect taste and safety while preserving the minerals your body uses. If you’re on well water or live in an area with known contamination, a reverse osmosis system with a remineralization cartridge handles the heavy lifting without leaving your water mineral-free.
If you prefer bottled water, look for brands that list mineral content on the label. European mineral waters with moderate mineralization deliver genuinely useful amounts of calcium and magnesium. North American spring waters vary enormously, so check the numbers rather than trusting the imagery on the label. Either way, glass bottles avoid the microplastic issue that comes with plastic packaging.
The single most important factor is drinking enough water, period. Two liters a day from almost any safe source keeps you well hydrated. But if you’re choosing between options of equal convenience and cost, water that still contains its minerals gives you a small, steady health advantage that compounds over years.