Spring water is water that comes from an underground source and flows naturally to the earth’s surface. That’s the simple version, but the term also carries a specific legal definition that dictates what bottled water companies can and can’t put on their labels. Understanding what qualifies as spring water helps you make sense of what you’re actually buying when you pick up a bottle at the store.
How Springs Form Underground
A spring is a spot where groundwater finds its way to the surface without human intervention. This water starts as rain or snowmelt that seeps into the ground, passes through layers of rock and soil, and collects in underground reservoirs called aquifers. When conditions are right, that stored water emerges at the surface.
There are a few ways this happens. In a depression spring, the water table simply intersects with the ground surface and overflows, like a bathtub filled past its rim. Surface springs form when a water-absorbing rock layer sits on top of a layer that blocks water, and the two meet the ground at an angle that lets water seep out. Artesian springs are the most dramatic: water gets trapped in an aquifer under pressure from surrounding rock, and when there’s an opening, it’s pushed upward and out, sometimes with considerable force. In all cases, the water has been naturally filtered through materials like limestone, sandstone, and clay on its journey underground.
The Legal Definition of Spring Water
In the United States, the FDA regulates bottled water under 21 CFR 165.110, and the rules for labeling something “spring water” are specific. The water must be collected at the spring itself or through a borehole that taps into the same underground formation feeding the spring. There must be a natural force causing the water to flow to the surface through a natural opening, and the location of the spring has to be identified.
Companies can use a borehole with a pump to draw water from deeper underground, but only if they can prove a measurable hydraulic connection between the borehole and the natural spring using accepted geological methods. The water pulled from that borehole must also have the same physical properties, composition, and quality as the water that flows to the surface on its own. In other words, you can’t drill into a completely different water source and call it spring water just because there’s a spring nearby.
What’s in Spring Water
Because spring water travels through rock and sediment before reaching the surface, it picks up dissolved minerals along the way. The most common are calcium, magnesium, potassium, and sodium. The exact mineral profile varies widely depending on the geology of the region. Water flowing through calcium-rich limestone will have a very different taste and composition than water filtered through volcanic rock.
This mineral content is actually what gives different spring water brands their distinct flavors. Some taste noticeably “harder” or more mineral-forward, while others taste clean and neutral. European regulators classify water as “calcic” when calcium exceeds 150 mg per liter, or “magnesiac” when magnesium tops 50 mg per liter, but U.S. labels don’t typically break this down for consumers.
Spring Water vs. Purified Water
The biggest difference is the source and how much processing happens. Spring water comes from a specific underground source and is considered naturally pre-filtered by the rock it passes through. It gets tested and may undergo basic treatment, but the goal is to preserve its natural character. Purified water, on the other hand, usually starts as tap water or generic groundwater and goes through intensive processing: reverse osmosis (forcing water through membranes to strip out minerals), distillation (boiling water into steam and recondensing it), or deionization. The result is water with virtually no mineral content.
Neither is inherently safer than the other. Both must meet FDA safety standards before being sold. The choice comes down to whether you prefer water with its natural mineral profile intact or water that’s been stripped to a blank slate.
Spring Water vs. Mineral Water
In the U.S., mineral water must contain between 500 and 1,500 mg per liter of total dissolved solids, a measure of all the minerals combined. Spring water has no such minimum. So mineral water is essentially a more mineral-dense category, though both can come from underground sources. In Europe, the distinction barely exists: any naturally sourced water with any level of mineralization can be called mineral water. Canada takes yet another approach, allowing “mineral water” and “spring water” to be used interchangeably on labels.
Marketing Terms That Sound Like Spring Water
Labels like “glacier water,” “mountain water,” or “artesian water” aren’t always regulated the same way as “spring water.” In Canada, glacier water has no formal legal definition, though regulators reference Alaska’s criteria: the water should come from a stream flowing directly from a glacier without being diluted by non-glacial sources, and its dissolved solids should remain low. Canadian regulators also prohibit misleading imagery on labels. Depicting a mountain scene on water sourced from flat prairie land, for example, is considered deceptive.
In the U.S., these marketing terms can be vague. “Mountain spring water” might genuinely come from a mountain spring, or it might be a brand name with no geographic meaning. The safest way to know what you’re getting is to look for the specific designation “spring water” on the label, which is the term with actual regulatory teeth.
Safety Standards for Bottled Spring Water
The FDA is responsible for bottled water safety, and it models its standards on those the EPA sets for public tap water. Each time the EPA establishes a new contaminant limit, the FDA either adopts it for bottled water or explains why it isn’t necessary. In some cases, bottled water standards are actually stricter. The EPA allows up to 15 parts per billion of lead in tap water because lead can leach from aging pipes between the treatment plant and your faucet. Bottled water, which never touches lead pipes, has a limit of just 5 ppb.
Environmental Considerations
Commercial spring water extraction draws from the same aquifers that feed local streams, wetlands, and ecosystems. When pumping exceeds the rate at which an aquifer naturally recharges, the effects ripple outward. According to the U.S. Geological Survey, groundwater pumping can intercept water that would otherwise discharge into streams and lakes, or accelerate the rate at which surface water drains into depleted aquifers. In the Ipswich River basin in Massachusetts, surface water flows have been measurably reduced by groundwater development. Along the Santa Cruz River south of Tucson, Arizona, the water table has dropped more than 100 feet due to pumping, leading to significant loss of streamside vegetation and wildlife habitat.
These examples involve all forms of groundwater extraction, not just bottled water operations. But large-scale spring water bottling plants that pull millions of gallons per year from a single source can contribute to localized depletion, particularly during droughts or in areas where aquifer recharge is slow.