Purified water is safe to drink and is one of the most common types of bottled water sold. It goes through processing that removes at least 99% of dissolved solids, chemicals, and bacteria, producing some of the cleanest drinking water available. But “cleanest” doesn’t automatically mean “healthiest,” and there are real tradeoffs worth understanding before you make it your primary water source.
What Makes Water “Purified”
Under U.S. federal regulations, water can be labeled “purified” if it has been treated by distillation, deionization, reverse osmosis, or another suitable process and meets the standards set by the United States Pharmacopeia. These processes strip out virtually everything dissolved in the water: minerals, salts, metals, chlorine, pesticides, and bacteria. The result is water with an extremely low concentration of total dissolved solids (TDS).
Purified water is different from spring water or mineral water, which retain naturally occurring minerals picked up from underground rock. It’s also different from standard filtered tap water, which removes some contaminants but typically leaves minerals intact. Think of purified water as a blank slate: nearly everything has been taken out.
How Purification Works
The two most common methods are reverse osmosis (RO) and distillation. Reverse osmosis pushes water through a membrane with pores small enough to block most contaminants, removing roughly 90 to 99% of salts, chemicals, bacteria, and heavy metals. It can be less effective against certain smaller molecules like some pesticides and PFAS compounds.
Distillation boils water into steam and then condenses it back into liquid, leaving behind 99% or more of dissolved solids, bacteria, and minerals. Because it relies on a phase change from liquid to gas and back, distillation is generally more thorough at removing a wider range of contaminants, including nitrates, PFAS, and microplastics. Both methods produce water that qualifies as purified, but distillation tends to strip out slightly more.
How It Tastes
Purified water often tastes flat or “empty” compared to tap or spring water. That’s because the minerals that give water its flavor, primarily calcium, magnesium, potassium, and bicarbonates, have been removed. Tap water with a high TDS can taste bitter or carry an unpleasant chlorine flavor, so many people actually prefer the neutral taste of purified water. Others find it bland and unsatisfying. It’s largely a matter of personal preference, but the flat taste is a direct consequence of the purification process doing exactly what it’s designed to do.
The Missing Minerals Problem
This is where purified water gets more complicated. Removing contaminants also removes beneficial minerals, particularly calcium and magnesium, that your body uses every day. Drinking water isn’t the primary source of these minerals for most people, but research suggests the supplemental intake from water matters more than its small percentage of your daily total might suggest. Even in countries with varied diets, food alone may not fully compensate for the absence of calcium and especially magnesium in drinking water.
The concern grows if you also cook with purified water. Demineralized water used for cooking can leach essential minerals out of vegetables, meat, and grains. Losses can reach up to 60% for magnesium and calcium, and even higher for trace elements like copper (66%), manganese (70%), and cobalt (86%). Over time, this compounds the mineral gap.
Some studies have linked long-term consumption of low-mineral water to a higher risk of bone fractures in children, certain cardiovascular events, pregnancy complications like preeclampsia, and low birth weight. Water low in magnesium specifically has been associated with a higher risk of motor neuronal disease. These are associations, not proof of direct causation, but the pattern is consistent enough that the World Health Organization has flagged demineralized drinking water as a potential health concern.
What Happens Inside Your Body
Your cells maintain a careful balance of minerals and water on either side of their membranes. When you drink water with very low mineral content, it can subtly shift the concentration of sodium, potassium, magnesium, and calcium in your body fluids. This changes what scientists call tonicity, essentially the pulling force that determines how much water moves into and out of your cells.
In practical terms, your body is well equipped to handle this in the short term. Your kidneys adjust, and the food you eat provides minerals. But chronic consumption of demineralized water without mineral supplementation from other sources can gradually lower blood levels of key electrolytes. Low magnesium, low calcium, and low potassium in the blood are well-documented clinical conditions with real symptoms: muscle cramps, fatigue, irregular heartbeat, and weakened bones over time.
The pH Factor
Purified water, particularly distilled water, tends to be slightly acidic. Lab measurements put distilled water at a pH around 5.4 to 5.7, compared to roughly 7.5 for tap water and home-filtered water. This happens because purified water readily absorbs carbon dioxide from the air, forming a mild carbonic acid. The acidity is very slight and your body buffers it easily, so it’s not a health risk on its own. But it’s one reason purified water tastes different from what comes out of your tap.
Microplastics in Bottled Purified Water
If you’re buying purified water in plastic bottles, there’s an ironic tradeoff. Research consistently finds higher microplastic concentrations in bottled water than in tap water, likely because the plastic packaging itself sheds particles into the water. Reported microplastic levels in single-use plastic bottles can be orders of magnitude higher than what’s found in household tap water. One analysis found tap water samples contained 0.09 to 0.57 micrograms per liter of microplastics, while bottled water concentrations were significantly higher. If avoiding contaminants is the reason you’re drinking purified water, buying it in plastic bottles may partially undermine that goal.
Remineralization Filters
Many home reverse osmosis systems now include an additional “alkaline” or remineralization stage that adds calcium, magnesium, and potassium back into the water after purification. This addresses both the taste issue and the mineral gap. The water passes through a mineral cartridge as a final step, raising the pH closer to neutral and restoring a more natural flavor profile. If you’re installing a home RO system, a six-stage model with a remineralization filter is a practical way to get the contaminant removal benefits of purified water without the downsides of drinking mineral-free water long term.
Who Benefits Most From Purified Water
Purified water makes the most sense when your source water is unreliable. If you’re dealing with well water contaminated by heavy metals, agricultural runoff with nitrates and pesticides, or municipal water with known lead or PFAS issues, the thorough contaminant removal of purification is genuinely protective. It’s also commonly used in medical settings and for people with compromised immune systems who need water free of bacteria and parasites.
For someone whose tap water already meets safety standards and tastes fine, the benefits of switching to purified water are smaller, and the mineral loss becomes a more relevant consideration. The best approach for most people is filtered water that removes harmful contaminants while leaving beneficial minerals in place, or purified water with minerals added back in. Drinking purified water occasionally, like grabbing a bottle at the store, is perfectly fine. Making it your only water source for years without considering mineral intake is where the potential issues emerge.