Purified water and spring water are not the same thing. They differ in where they come from, how they’re processed, and what ends up in the bottle. Purified water is defined by its treatment method, while spring water is defined by its source. That distinction affects mineral content, taste, and which situations each type is best suited for.
How Each Type Is Defined
The FDA regulates both purified and spring water under the same bottled water rules, but the labeling requirements are completely different. Spring water must come from an underground formation where water flows naturally to the earth’s surface. It can only be collected at the spring itself or through a borehole tapping into the same underground layer feeding the spring. Even when companies use pumps or other external force to collect it, the water must continue flowing naturally to the surface, and the bottler must be able to prove the borehole connects to the actual spring using accepted geological methods.
Purified water, on the other hand, can start as any water source, including tap water. What earns it the “purified” label is the treatment it undergoes. The water must be processed through distillation, reverse osmosis, deionization, or other methods that strip it down to no more than 10 parts per million of total dissolved solids. For comparison, typical tap water contains anywhere from 50 to 500 parts per million. The result is water that’s been cleaned to a very specific, measurable standard regardless of where it started.
Mineral Content Differences
This is where the two types diverge most noticeably. Spring water retains the minerals it picks up while moving through underground rock and soil. A study published in the Journal of General Internal Medicine analyzed 28 North American spring waters and found calcium levels ranging from 0 to 76 mg/L, magnesium from 0 to 95 mg/L, and sodium from 0 to 15 mg/L. The variation is huge because every spring has different geology. Some spring waters are mineral-rich, others are nearly bare.
Purified water, by design, has almost nothing left in it. The aggressive filtration processes remove virtually all minerals along with contaminants. Some brands add small amounts of minerals back in after purification for taste, but the baseline product is essentially stripped clean. This is why purified water often tastes “flat” or neutral compared to spring water, which can have a subtle mineral flavor that varies from brand to brand.
Health Considerations
For most people, drinking either type of water is perfectly fine. You get the vast majority of your minerals from food, not water. But there are situations where the difference matters more than you might expect.
Research on demineralized water has raised concerns about long-term exclusive use. An expert consensus group found that hard water (water with higher mineral content) is probably associated with a somewhat lower risk of cardiovascular disease, with magnesium being the likely contributor to that benefit. The bigger issue, though, is cooking. When demineralized water is used to prepare food, it pulls minerals out of vegetables, meat, and grains at much higher rates than mineral-containing water does. Losses can reach up to 60% for magnesium and calcium, and even higher for trace elements like copper (66%), manganese (70%), and cobalt (86%). Using hard or mineral-rich water for cooking actually preserves those nutrients and can even increase calcium content in some foods.
If purified water is your primary drinking and cooking water, you’re not in danger of a mineral deficiency on its own. But if your diet is already low in mineral-rich foods, the cumulative effect of cooking with demineralized water could widen that gap over time.
Taste and Everyday Use
Taste is subjective, but the mineral content of spring water gives it a character that purified water lacks. Some people prefer the clean, blank taste of purified water. Others find it too flat and prefer the subtle earthiness of a spring water. If you’re making coffee or tea, the minerals in spring water can actually affect extraction and flavor, which is why some coffee enthusiasts are particular about their water’s mineral profile.
For drinking, either works. The choice is largely about personal preference and what you’re willing to pay, since spring water often costs more due to the sourcing requirements.
When the Type of Water Actually Matters
Certain appliances and medical devices perform better with one type over the other. CPAP machines, which many people use for sleep apnea, are a good example. Manufacturers and sleep experts recommend distilled water (the most aggressively purified type) for CPAP humidifiers. Even regular purified water can contain trace minerals that build up in the machine over time. Spring water, with its higher mineral content, accelerates that buildup and can leave deposits in the humidifier reservoir. The same principle applies to steam irons, humidifiers, and autoclaves: the fewer minerals in the water, the less scale and residue you’ll deal with.
For baby formula, purified water is generally preferred because it offers a more predictable mineral content. Spring water’s mineral levels vary so widely between brands that it’s harder to know exactly what your baby is getting. Some spring waters contain sodium or fluoride levels that may not be appropriate for infants.
Safety and Contaminant Testing
Both types are regulated by the FDA, which is required to match or exceed the EPA’s standards for public drinking water when it comes to contaminant limits. This includes newer concerns like PFAS, the persistent chemicals sometimes called “forever chemicals.” FDA testing of bottled water found detectable PFAS levels in some samples of both purified and spring water, though none exceeded the maximum contaminant levels set by the EPA for public drinking water. Neither type is inherently safer than the other from a contamination standpoint. Both must meet the same federal limits for things like lead, arsenic, and microbial contaminants.
The purification process does give purified water a theoretical edge in removing contaminants that might slip through less intensive treatments, but spring water bottlers also test and treat their water to meet federal standards. The difference is that spring water treatment is designed to preserve the water’s natural mineral character, while purification is designed to strip essentially everything out.