The bottled water aisle presents a dizzying array of choices. The “best” type of bottled water is a personal conclusion that balances taste preference, desired mineral content, budget, and environmental concerns. Understanding the fundamental differences in how water is sourced and processed is the first step toward making an informed choice.
Differentiating the Main Types of Bottled Water
Bottled water is legally categorized based on its source and the treatment methods it undergoes. Spring water is sourced from an underground formation where water naturally flows to the Earth’s surface. It can be collected at the natural opening or through a borehole connected to the spring. It is usually minimally processed to maintain its natural composition.
Purified water is defined by the rigorous treatment it receives rather than its origin, which can be any municipal or natural source. This water undergoes processes like reverse osmosis, distillation, or deionization to remove dissolved solids and contaminants. The resulting product is essentially pure H₂O, often having a neutral, clean taste because natural minerals have been stripped away.
Mineral water is a specific type of naturally sourced water that must originate from a protected underground source and be bottled there. Its defining characteristic is a constant level of Total Dissolved Solids (TDS), which must be at least 250 milligrams per liter (mg/L). The minerals and trace elements in this water must be naturally occurring and cannot be added artificially.
Artesian water is collected from a well that taps into a confined aquifer. This aquifer is situated between impermeable layers of rock or clay. Natural pressure often forces the water to the surface without the need for pumping. Like spring water, artesian water is valued for its naturally occurring mineral composition and is typically only filtered to remove large particulates.
Evaluating Water Quality: pH, TDS, and Mineral Content
Water quality is often discussed in terms of Total Dissolved Solids (TDS) content. TDS is a quantitative measure of inorganic salts, minerals, and organic matter dissolved in the water, measured in parts per million (ppm) or mg/L. TDS is the primary factor influencing the taste and “mouthfeel” of water. Waters with low TDS, such as purified water, are often described as tasting flat or light, while mineral water has a higher TDS and a more distinct taste.
The pH scale measures how acidic or alkaline a substance is, with 7.0 being neutral. Alkaline water is marketed with a higher pH, typically between 8 and 10, often achieved by adding minerals like calcium and magnesium. Proponents claim alkaline water can neutralize acid in the body. However, the scientific consensus is that the body’s pH is tightly regulated by the kidneys and lungs, making it unlikely that drinking water would cause a significant, lasting change.
While most health claims remain unproven, some small studies suggest that alkaline water may help reduce acid reflux symptoms or improve hydration after intense exercise. Purified water manufacturers sometimes add minerals, referred to as electrolytes, back into the product. These added minerals primarily enhance flavor and compensate for the flat taste resulting from aggressive purification processes like reverse osmosis.
Practical Considerations: Packaging and Safety
The most common packaging for single-serving bottled water is Polyethylene Terephthalate, known as PET plastic. A frequent consumer concern is Bisphenol-A (BPA) leaching from the packaging. However, PET plastic does not contain BPA. BPA is typically associated with polycarbonate plastics, which are used for large, reusable water containers, such as three- and five-gallon jugs.
A more current concern is the presence of microplastics and nanoplastics, which have been detected in bottled water. Research indicates that an average liter of bottled water may contain hundreds of thousands of these tiny plastic particles. Storing PET plastic bottles in warm environments or reusing them may increase the potential for chemical migration into the water.
All bottled water sold commercially in the United States is regulated by the Food and Drug Administration (FDA) as a packaged food product. The FDA mandates that its regulations must be at least as protective of public health as the standards set by the Environmental Protection Agency (EPA) for tap water. This oversight ensures that all water types—spring, purified, or mineral—must meet safety standards for contaminants before reaching the consumer.