Understanding the Differences: Source and Processing
For many consumers, the bottled water aisle can be confusing, with labels like "spring" and "purified" often used interchangeably in marketing. However, these two types of water are fundamentally different in their origin and the way they are processed. Understanding this distinction is crucial for making an informed choice that aligns with your health goals and taste preferences.
What Is Spring Water?
Spring water originates from an underground formation, or aquifer, from which water naturally flows to the Earth's surface. As it travels through layers of rock and soil, it undergoes a natural filtration process that enriches it with a unique blend of minerals, such as calcium, magnesium, and potassium. This mineral content gives spring water its distinctive, often crisp and refreshing, taste.
For commercial bottling, spring water is collected either directly from the surface spring or from a borehole that taps into the underground source. By law, the composition of the water collected from the borehole must be identical to the water in the surface spring. This water undergoes minimal processing, primarily filtration and disinfection (often with ozone or UV light), to ensure safety while preserving its natural mineral profile. While companies may transport the water in tanker trucks to a bottling facility, regulations require it to be chlorinated for transport and then dechlorinated later, which is why minimal filtration is still required.
What Is Purified Water?
In contrast to spring water, purified water can originate from any source, including municipal tap water. Its defining characteristic is the rigorous purification process it undergoes to remove contaminants and dissolve solids. The Food and Drug Administration (FDA) and Environmental Protection Agency (EPA) have strict standards for purified water, requiring it to contain less than 10 parts per million (ppm) of total dissolved solids (TDS).
The purification methods commonly used include:
- Reverse Osmosis (RO): This process forces water through a semi-permeable membrane to remove dissolved inorganic solids, chemicals, and bacteria.
- Distillation: Water is boiled into steam, which is then condensed back into a pure liquid, leaving behind contaminants and minerals.
- Deionization: A process that uses ion-exchange resins to extract dissolved salts and other ions from the water.
Because most minerals are removed during this intensive process, purified water typically has a neutral, consistent, and flat taste. Some producers may add minerals back for taste consistency.
The Importance of Total Dissolved Solids (TDS)
Total Dissolved Solids (TDS) is a measure of the concentration of all inorganic and organic substances dissolved in water. This is a key metric for distinguishing between spring and purified water.
TDS in Spring Water: Because spring water picks up minerals naturally from its underground environment, its TDS level can vary significantly depending on the source. A higher TDS level contributes to its distinct taste and potentially beneficial mineral content.
TDS in Purified Water: By definition, purified water has an extremely low TDS level, below 10 ppm, as the purification methods are designed to strip away virtually everything except the H2O molecules.
Comparison: Spring Water vs. Purified Water
To further clarify the differences, here is a comparison table outlining the key attributes of spring water and purified water.
| Feature | Spring Water | Purified Water |
|---|---|---|
| Source | Natural underground aquifer or spring | Any source, including tap water |
| Processing | Minimal filtration (ozone/UV disinfection) to ensure safety while preserving natural minerals | Extensive processing (RO, distillation, deionization) to remove nearly all contaminants |
| Mineral Content | Naturally rich in minerals like calcium, magnesium, and potassium | Stripped of most minerals, resulting in very low mineral content |
| TDS Level | Varies by source, generally higher than purified water | Very low; below 10 parts per million (ppm) |
| Taste | Often described as crisp, refreshing, and mineral-rich | Consistent, neutral, or flat taste |
| Regulation | Regulated as bottled water by the FDA, with identity standards for spring water | Regulated by the FDA, with specific quality standards for purity |
Conclusion
In summary, spring water is not considered purified water because its defining characteristic is its natural origin and mineral content, not a process of intensive contaminant removal. Spring water is minimally treated to ensure safety, while maintaining the minerals that give it flavor. Purified water, on the other hand, is a product of rigorous, technology-driven processes designed to remove virtually all dissolved solids and contaminants, regardless of its original source. The choice between them ultimately comes down to personal preference—whether you favor the natural, mineral-rich taste of spring water or the consistent, ultra-clean profile of purified water.
For more information on water quality standards, you can consult the International Bottled Water Association's website, which details FDA regulations and water types.
Understanding Regulatory Oversight
It's important to note that both spring and purified bottled waters are regulated as packaged food products by the U.S. Food and Drug Administration (FDA). These regulations are designed to be at least as stringent and protective of public health as the EPA's standards for tap water, with specific identity and quality standards for different water types. This ensures that regardless of the label, the water you purchase is safe for consumption. The primary difference is the standards of identity they must meet: spring water is identified by its source and minimal treatment, whereas purified water is defined by its low TDS level and the intensive processing it receives.
