Spring, Mineral, Purified, Artesian: What Bottled Water Labels Actually Mean

“Spring,” “mineral,” “purified,” “artesian,” and “distilled” are not marketing words—each one is a legally defined term under a U.S. Food and Drug Administration regulation (21 CFR 165.110), and a bottler cannot use it unless the water meets the definition. Spring water must flow naturally to the surface from an underground formation. Mineral water must contain at least 250 parts per million of dissolved solids, all naturally occurring. Purified water has been run through distillation, deionization, or reverse osmosis. And if the water came from a city tap and was not purified to that standard, the label has to say “from a community water system” or “from a municipal source.” Once you know the vocabulary, a bottle’s front panel tells you exactly what you are buying.

Who Sets the Rules

Tap water is regulated by the Environmental Protection Agency under the Safe Drinking Water Act. Bottled water is a packaged food, so it falls to the FDA, which sets both the quality limits and the “standard of identity”—the rulebook for what each name on the label means. That rulebook lives in Title 21 of the Code of Federal Regulations, section 165.110, and it is short enough to read in one sitting. The definitions below are paraphrased from it.

The Terms, Decoded

Spring water. Water from an underground formation from which water flows naturally to the surface. It can be collected at the spring itself or through a bore hole that taps the same formation, but if a bore hole is used, water must still be flowing naturally at the spring’s natural opening, and the bottler must be able to show a measurable hydraulic connection between the two. The spring’s location has to be identified.

Mineral water. Water containing not less than 250 ppm total dissolved solids, from a geologically and physically protected underground source, with a constant level and proportion of minerals at the point where it emerges. No minerals may be added. If the dissolved-solids level is below 500 ppm, the label must say “low mineral content”; above 1,500 ppm, “high mineral content.”

Artesian water. Water from a well tapping a confined aquifer in which the water level stands above the top of the aquifer—in other words, an aquifer under natural pressure. It may be pumped, but the pressure has to be there to begin with.

Well water and ground water. Well water is simply water from a hole bored or drilled into an aquifer. Ground water is water from a saturated underground zone that is not under the direct influence of surface water. Neither term implies any particular mineral content or treatment.

Purified water. Water produced by distillation, deionization, reverse osmosis, or another suitable process that meets the U.S. Pharmacopeia definition of purified water. A bottler may also use the more specific process name—“distilled water,” “deionized water,” or “reverse osmosis water”—or the phrase “purified drinking water.” The source can be anything, including a municipal supply; the name describes the treatment, not the origin.

Sparkling bottled water. Water that, after treatment and possible replacement of carbon dioxide, contains the same amount of CO₂ it had at the source. A plain seltzer made by carbonating tap water is a soft drink under FDA rules, not “sparkling bottled water.”

Sterile water. Water that meets the Pharmacopeia’s sterility test. This is the only category that is actually free of microorganisms, and it is a medical product more than a beverage.

The Line That Matters Most

The single most useful sentence in the regulation is the one about municipal sources. When bottled water comes from a community water system and has not been treated to the purified or sterile standard, the label must state “from a community water system” or “from a municipal source,” immediately next to the product name, in type at least half the size of the name. So a bottle that says only “purified water” may well have started as tap water—legally, and with no disclosure required, because the treatment earned the name. A bottle that says “drinking water, from a municipal source” is tap water that was filtered and bottled without meeting that bar.

None of this makes one category safer to drink than another; the FDA quality limits apply across the board. What the terms tell you is where the water came from and what was done to it, which is exactly the information the front of a bottle is designed to imply without stating.

What This Means for a Refillable Bottle

Once you can read the label, the value proposition of most single-use water gets clearer. “Purified water” is treated water in a disposable container. The same treatment is available at home from a filter pitcher or an under-sink reverse-osmosis unit, and an insulated stainless bottle carries it without the plastic. If you like the taste of a particular mineral or spring water, that is a real preference the definitions help you name—and a reason to buy that specific water rather than a generic “purified” bottle that is functionally your tap.

It is also the reason NuRich’s long-term goal is a purified-water facility rather than a bottling line: the point is the water standard, not the throwaway package around it.

Shop NuRich

The 32 oz NuRich Insulated Bottle ($29.99) holds a full day of whatever water you choose and keeps it cold, and the 18 oz Original ($14.99) fits a bag or cup holder. Browse the full lineup at livenurich.com.

This post is for informational purposes only and is a plain-language summary of a federal regulation, not legal advice. Refer to the regulation itself for exact wording, and consult a healthcare professional for guidance on drinking-water choices specific to you.

Sources: U.S. Food and Drug Administration, 21 CFR §165.110 Bottled water — standard of identity for artesian, ground, mineral (≥250 ppm TDS; low/high mineral content statements at <500 / >1,500 ppm), purified, sparkling, spring, sterile, and well water; “from a community water system” / “from a municipal source” labeling requirement (ecfr.gov/current/title-21/chapter-I/subchapter-B/part-165/subpart-B/section-165.110) • U.S. EPA, Safe Drinking Water Act overview — EPA regulates public tap water (epa.gov/sdwa) • NuRich program information (purified-water facility goal)