Bottled spring water comes from underground formations where water naturally flows to the earth’s surface. That’s not just marketing language. Under federal regulations, a company can only label its product “spring water” if the water originates from a specific type of underground source with a natural opening where water emerges on its own.
What the Law Requires
The FDA defines spring water as water “derived from an underground formation from which water flows naturally to the surface of the earth.” To carry the label, the water must be collected either directly at the spring or through a borehole that taps into the same underground formation feeding it. Even when companies use a borehole and mechanical pumps to extract the water, the natural spring must continue flowing on its own at the surface. The company also has to prove, using accepted geological methods, that the borehole draws from the same underground layer as the natural spring.
This is a stricter standard than it might sound. The water must have the same composition and physical properties as what flows naturally to the surface, and minerals cannot be added or removed. The spring’s location must be identified, giving regulators a way to verify the claim.
How Springs Form Underground
Rain and snowmelt seep into the ground and slowly travel downward through soil, sand, and porous rock until they reach a layer that holds and transmits water, called an aquifer. According to the U.S. Geological Survey, aquifers form when porous rock layers sit between less permeable materials like clay or shale. Water moves through these formations over years or even decades, picking up dissolved minerals along the way.
Springs appear where geological conditions force that underground water back to the surface. A tilted rock layer, a crack in an overlying barrier, or a hillside that intersects the water table can all create a natural opening. In some cases, the water is under enough pressure from surrounding rock that it pushes upward on its own, creating what’s known as an artesian spring. These pressurized systems are common sources for bottled water because the natural force driving the flow is consistent and reliable.
The mineral content of any given spring depends entirely on what rock the water passed through. Limestone-rich formations add calcium. Dolomite contributes magnesium. The time water spends underground also matters: longer contact with rock means higher mineral concentrations. Some springs produce water with calcium levels above 150 mg/L, while others deliver water with magnesium above 50 mg/L. These minerals are what give different spring waters their distinct taste.
Where Major Brands Source Their Water
The specific spring matters, and well-known brands source from very different parts of the world. Evian draws from mountain springs in the French Alps, where water filters through glacial rock formations for roughly 15 years before emerging. Fiji bottles from an artesian aquifer on the island of Viti Levu, where volcanic rock gives the water its silica-heavy profile. Arrowhead (owned by Nestlé) sources from various mountain springs across California and Colorado.
Labels are required to identify the water source. In some states, like Pennsylvania, bottled water labels must include the name of the water supplier, the product trade name, and the water source. When the source is a municipal water system rather than a natural spring, that has to appear on the label too. This is one of the easiest ways to check whether what you’re buying is genuinely spring-fed or reprocessed tap water.
What Happens Between the Spring and the Bottle
Spring water goes through less processing than other types of bottled water, but it’s not untreated. At the source or in the bottling plant, the water is first filtered to remove physical particles like sediment. This initial filtration also serves as a barrier against bacteria, viruses, and parasitic cysts. After that, most bottlers disinfect the water using either ozone or ultraviolet light, both of which kill microorganisms without leaving chemical residues or altering the mineral profile.
The key constraint is that filtration can only go so far. Unlike purified water, which may be stripped down through reverse osmosis or distillation, spring water must retain its natural mineral content. If a company removes the minerals, it can no longer call the product spring water. This is why spring water typically has a more noticeable taste compared to purified water, which tends toward neutral.
How Spring Water Differs From Other Bottled Water
The bottled water aisle includes several categories that sound similar but follow different rules:
- Spring water must come from a natural underground source and retain its original minerals. Processing is minimal.
- Purified water can start as any water source, including municipal tap water, and undergoes aggressive filtration (distillation, reverse osmosis, or carbon filtration) to remove contaminants. Most minerals are stripped out in the process.
- Mineral water must contain at least 250 parts per million of dissolved solids from a geologically protected underground source. No minerals can be added after extraction.
The practical difference comes down to what’s in the water and where it started. Spring water sits in the middle: more natural character than purified water, but not necessarily as mineral-dense as water specifically labeled “mineral water.” Both spring and purified water are regulated by the FDA and must meet safety standards, but the standards reflect their different origins. Spring water quality standards are tied to the source itself, while purified water standards focus on the effectiveness of the filtration process.
What the Minerals Actually Do
The dissolved minerals in spring water aren’t just a flavor difference. Calcium-rich waters (above 150 mg/L) can contribute meaningfully to daily calcium intake, which is relevant for people who don’t consume much dairy. Magnesium-rich waters (above 50 mg/L) support digestion and muscle function. Some spring waters contain significant bicarbonate (above 600 mg/L), which can help neutralize stomach acid.
These concentrations vary enormously from one spring to another. A bottle of Evian won’t deliver the same mineral profile as a bottle of Fiji, because the geology at each source is completely different. If mineral content matters to you, the nutrition label on the bottle will list the specific concentrations. Comparing a few brands side by side reveals just how much the underground journey shapes what ends up in your glass.