The best water to drink is water that’s free of harmful contaminants while still containing naturally occurring minerals like calcium and magnesium. For most people in the United States, filtered tap water hits that sweet spot: it’s regulated, affordable, and retains beneficial minerals that highly purified alternatives strip out. But the real answer depends on what’s in your local supply and how you choose to filter it.
Why Minerals in Water Matter
Water isn’t just hydration. It’s a meaningful source of calcium and magnesium, two minerals essential for bone strength, sleep quality, immune function, and blood sugar regulation. Standard tap water contains roughly 46 mg/L of calcium and 7 mg/L of magnesium. Those numbers might sound small, but they add up across the eight or more glasses you drink daily, and your body absorbs minerals from water more readily than from many foods.
Research on children’s bone health illustrates this clearly. Kids who regularly drank very low-mineral water had lower bone mineral density and slower height growth compared to those drinking mineral-rich water. Mineral water also appears to support bone metabolism by reducing the release of a hormone that triggers bone breakdown. And because calcium supplements carry some cardiovascular risk, getting minerals from water and food is increasingly seen as the safer approach.
Tap Water vs. Bottled Water
Municipal tap water in the U.S. is regulated under the Safe Drinking Water Act, which sets legal limits for dozens of contaminants. Every year, your local utility publishes a Consumer Confidence Report (sometimes called a water quality report) that lists exactly what was found in your water over the past 12 months. The CDC recommends looking for a column labeled “violations” or “meets standard” to quickly see if anything exceeded safe levels.
Bottled water, by contrast, is regulated by the FDA under different standards and isn’t necessarily cleaner. A study from Ohio State University found that bottled water contained three times as many nanoplastic particles as treated tap water. Plastic bottles themselves are the likely source, meaning you may be trading one concern for another. If you prefer the convenience of bottled water, glass-bottled mineral or spring water avoids the microplastic issue while preserving mineral content.
How Filtration Changes Your Water
Not all filters do the same thing, and some remove more than you’d want them to.
- Activated carbon filters (like Brita pitchers and fridge filters) are effective at removing chlorine taste, many organic chemicals, and a broad range of micropollutants. They leave calcium and magnesium largely intact, making them a solid everyday choice.
- Reverse osmosis (RO) systems strip out dissolved solids, heavy metals, and most contaminants, but they also slash calcium to about 3 mg/L and magnesium to nearly zero. That’s a 94% drop in calcium and a 99% drop in magnesium compared to unfiltered tap water.
- Distillation produces even purer water than RO, removing virtually all minerals and impurities through evaporation and condensation. It’s the cleanest water you can get, but also the most mineral-depleted.
- Ion exchange resins excel at targeting specific contaminants like PFAS (the “forever chemicals” now under strict EPA limits of 4 parts per trillion for PFOA and PFOS). They’re less common in home setups but increasingly available in specialized filter systems.
If you use an RO system and want to keep the contaminant removal without losing minerals, look for units that include a remineralization stage. These add calcium and magnesium back after filtration.
What About Alkaline Water?
Alkaline water, which has a pH above 7, is marketed with claims about neutralizing acid in the body, improving energy, and slowing aging. The evidence doesn’t support most of those claims. Harvard Health Publishing notes that alkaline water may offer temporary relief from acid reflux symptoms by neutralizing stomach acid on contact, but it’s less effective than standard antacids and far less effective than medications designed for that purpose.
Your body tightly regulates its own pH through your kidneys and lungs. Drinking water with a higher pH doesn’t meaningfully shift your blood chemistry. If you enjoy the taste of alkaline water, it won’t hurt you, but there’s no clinical reason to pay a premium for it.
Sparkling and Mineral Water
Sparkling mineral water is a genuinely good option if you prefer something with more character than flat tap water. Natural mineral water from spring sources often contains significant levels of calcium and magnesium, sometimes exceeding what you’d find in tap water depending on the geological source. The carbonation doesn’t reduce hydration in any meaningful way.
The main downside is cost. If you’re drinking several liters a day, sparkling mineral water gets expensive quickly compared to filtered tap. For people who struggle to drink enough water because they find it boring, though, carbonated water can make a real difference in daily intake.
Hydration Isn’t Just About the Water
Your body retains water more effectively when it arrives with some sodium and other solutes. Research published in The American Journal of Clinical Nutrition measured how long different beverages stayed in the body before being excreted. Plain water was assigned a hydration index of 1.0, and beverages with higher sodium content scored up to 1.24, meaning the body retained about 24% more fluid. In practical terms, young adults who drank a liter of a higher-sodium beverage produced roughly 215 fewer grams of urine over the following hours compared to plain water.
This doesn’t mean you need to buy electrolyte drinks for everyday hydration. But if you’re exercising heavily, spending time in heat, or recovering from illness, adding a pinch of salt or choosing a water with natural mineral content will keep you hydrated longer than ultra-pure water.
How to Check What’s in Your Tap Water
Before spending money on any filter or bottled water, find out what you’re actually working with. Your water utility is required to send you an annual water quality report, and most publish it online. The report will tell you where your water comes from (surface reservoir, groundwater, etc.), what contaminants were detected, and whether any exceeded EPA limits.
Pay attention to a few things in particular. Look for any listed violations first. Then check levels of lead, PFAS, and disinfection byproducts, which are the contaminants most commonly found at concerning levels in otherwise compliant systems. Chlorine will almost certainly show up, but at the levels used for disinfection it’s safe and serves an important purpose in killing waterborne pathogens.
If your water comes from a private well, it’s not covered by EPA regulations. You’ll need to test it yourself, ideally once a year, through a certified lab. State health departments typically maintain lists of approved testing services.
The Practical Bottom Line
For most people, the best water to drink is filtered tap water using an activated carbon filter. It removes chlorine taste and common organic contaminants while preserving the calcium and magnesium your body needs. If your local water report shows elevated PFAS or heavy metals, step up to a reverse osmosis system with remineralization. Skip the premium prices on alkaline water. And if you’re choosing bottled, opt for glass-bottled mineral or spring water over plastic to avoid tripling your microplastic exposure.