The best water to drink is whatever clean, safe water you’ll actually drink enough of. For most people in the United States, filtered tap water hits the sweet spot of safety, mineral content, and cost. But the answer gets more nuanced depending on what you’re optimizing for: mineral intake, contaminant avoidance, taste, or environmental impact. Here’s what the evidence says about each type.
Tap Water: Cheap and Mostly Safe
Municipal tap water in the U.S. is regulated under the Safe Drinking Water Act, with the EPA setting maximum contaminant levels for over 90 substances. For lead and arsenic, the EPA’s health-based goal is zero, meaning no amount is considered risk-free. The enforceable limits are higher than zero because of practical constraints, but most public systems stay well within them.
The real variable is your local system. Older homes with lead service lines or lead solder in pipes can introduce contamination after water leaves the treatment plant. Agricultural areas may have elevated nitrate levels. You can check your water utility’s annual Consumer Confidence Report (every system is required to publish one) or request a test kit from your local health department. If your tap water tests clean, it’s one of the best options available, and it costs a fraction of a cent per glass.
Mineral Water: A Surprising Nutrient Source
Natural mineral water contains calcium and magnesium dissolved from underground rock formations, and these minerals are highly absorbable. According to a WHO report, calcium from mineral-rich water is absorbed and retained at the same rate as calcium from milk. Magnesium from water averages around 59% bioavailability and is actually more bioavailable than magnesium from food sources, partly because the minerals are already in ionic form when dissolved in water.
This matters because both minerals play significant roles in health. Low magnesium intake is linked to higher blood pressure, insulin resistance, and increased cardiovascular risk. Inadequate calcium is associated with osteoporosis, colorectal cancer risk, and coronary artery disease. Drinking water with a meaningful mineral content (look for calcium above 80 mg/L and magnesium above 20 mg/L on the label) can meaningfully supplement what you get from food. Magnesium absorption from water increases further when you drink it with a meal, jumping from about 46% to 52%.
Not all bottled mineral water is created equal, though. Mineral concentrations vary enormously between brands. Check the label for specific calcium and magnesium numbers rather than trusting marketing language.
Filtered Water: The Practical Middle Ground
If your tap water has issues, or you just want an extra margin of safety, a home filter can address most concerns without the cost and waste of bottled water. The three main options work differently.
- Granular activated carbon (pitcher filters, fridge filters): Good for chlorine taste and some organic chemicals. Less effective against heavy metals and dissolved contaminants.
- Solid carbon block filters: More effective than granular carbon. Can reduce lead, PFAS (the “forever chemicals” found in many water supplies), and other heavy metals.
- Reverse osmosis systems: Force water through a membrane that blocks most dissolved substances, including heavy metals and many chemical contaminants. The tradeoff is that they also strip out beneficial minerals like calcium and magnesium, and they waste several gallons of water for every gallon they produce.
For most households, a solid carbon block filter offers the best balance. It removes the contaminants people worry about most while preserving the minerals that make water nutritionally useful. If you go with reverse osmosis, you’re essentially creating something close to purified water, so you’ll want to make sure your diet compensates for the lost mineral intake.
Bottled Water: What the Labels Mean
The FDA regulates bottled water labeling, and the terms on the bottle have specific legal definitions. “Spring water” must come from an underground source that flows naturally to the surface, collected either at the spring or from a borehole tapping the same formation. “Artesian water” comes from a pressurized underground aquifer. “Purified water” has been processed through distillation, reverse osmosis, or a similar method to remove dissolved substances.
These categories tell you about the water’s origin or processing, not necessarily its quality. A purified water and a spring water can both be perfectly safe. The bigger concern with bottled water is microplastics. A 2024 NIH-supported study found that a liter of bottled water contains an average of 240,000 tiny plastic particles. The long-term health effects of ingesting microplastics aren’t fully understood yet, but the sheer volume is striking, and it’s a reason to think twice about making bottled water your primary source.
There’s also the environmental cost. Single-use bottled water systems consume 11 to 31 times more energy than municipal tap water systems. Even reusable home-delivery jugs use only about 8 to 18% of the energy of single-use bottles, making them a far better option if you prefer delivered water.
Alkaline Water: Limited but Real Benefits
Alkaline water (typically pH 8 to 9.5) is marketed with broad health claims, most of which lack strong evidence. Your body tightly regulates its own blood pH regardless of what you drink. However, there is one specific scenario where alkaline water has demonstrated value: acid reflux. Water with a pH of 8.8 can help neutralize pepsin, a digestive enzyme that lodges in esophageal tissue during reflux episodes and continues causing damage. If you deal with frequent heartburn, alkaline water may offer some symptom relief.
For general hydration and health, though, alkaline water doesn’t outperform regular water. It’s not harmful, but it’s rarely worth the premium price unless you’re using it for reflux management.
Distilled Water: Clean but Empty
Distilled water has been boiled into steam and condensed back into liquid, removing virtually all minerals and contaminants. It’s the purest water you can drink, and it’s safe. The concern that distilled water “leaches minerals from your body” is overstated. You get the vast majority of your calcium, magnesium, and other minerals from food, so drinking distilled water won’t cause deficiencies in someone eating a balanced diet.
That said, you’re giving up the free mineral supplementation that comes with harder tap or mineral water. Over time, this adds up, especially for people whose diets are already marginal in calcium or magnesium. Distilled water also tastes flat to most people, which can make it harder to drink enough throughout the day.
Hydration Differences Between Water Types
A study published in The American Journal of Clinical Nutrition developed a “beverage hydration index” measuring how well different drinks keep you hydrated compared to still water. Sparkling water, for instance, produced no difference in urine output compared to still water, so choose whichever you prefer. Oral rehydration solutions (water with electrolytes and a small amount of sugar) scored significantly higher, with a hydration index of 1.54, meaning they retained about 54% more fluid than plain water after two hours.
For everyday hydration, the difference between water types is minimal. Plain water, sparkling water, and mineral water all hydrate you equally well. Electrolyte-enhanced water becomes more relevant during heavy exercise, illness, or any situation involving significant fluid loss.
The Bottom Line on Choosing Your Water
If your tap water tests clean, a simple carbon block filter gives you safe, mineral-rich water at the lowest cost and environmental impact. If you want a mineral boost, look for mineral water brands with high calcium and magnesium content on the label. Avoid making single-use bottled water your daily default: the microplastic exposure is substantial and the energy footprint is 10 to 30 times higher than tap. Distilled and reverse-osmosis water are fine if you prefer them, but you’re trading away beneficial minerals for purity you may not need.