The bottled water market is built on the promise of purity and convenience. While many choose bottled water for health, the term “healthiest” is complex and subjective, depending on personal dietary needs and the water’s chemical makeup. Evaluating a brand requires looking beyond marketing claims to understand the source, the filtration process, and the final chemical profile. This article provides a framework for evaluating bottled water quality, examining the scientific metrics and packaging considerations involved.
Differentiating Bottled Water Sources
Understanding the source is the first step in evaluating bottled water, as it dictates the regulatory classification and initial chemical composition. Bottled water falls into three primary categories based on origin and processing.
Purified water often originates from a municipal source (tap water) that undergoes rigorous treatment to remove contaminants and dissolved solids. This process, typically involving reverse osmosis or distillation, results in water that is nearly 99.9% pure, but it also strips away naturally occurring minerals.
Spring water must come from an underground formation where water flows naturally to the surface. Although it undergoes filtration to remove particles, it is not chemically treated and retains the unique mineral profile gathered from the rock layers. The mineral content of spring water varies significantly based on its geographic source.
Mineral water is defined by its consistent concentration of Total Dissolved Solids (TDS), which must be naturally present and cannot be artificially added. Regulations require mineral water to contain a minimum of 250 parts per million (ppm) of TDS, and it must be bottled directly at the source from a protected underground reservoir.
Chemical Criteria for Water Quality
Beyond the source, chemical criteria help determine water quality and potential health benefits.
pH Level
The pH level measures the water’s acidity or alkalinity on a scale of 0 to 14, with 7 being neutral. Although some brands market highly alkaline water (pH above 8), the body’s natural systems, particularly the kidneys, effectively maintain a stable blood pH. Therefore, the pH of drinking water is largely inconsequential to overall systemic balance for most people.
However, acidic water (low pH) may indirectly pose a risk by increasing corrosivity. This can lead to the leaching of heavy metals like lead and copper from plumbing systems in home environments.
Total Dissolved Solids (TDS)
A more relevant metric is Total Dissolved Solids (TDS), which quantifies the concentration of inorganic salts, minerals, and metals present in the water, measured in milligrams per liter (mg/L). Water with very low TDS, often purified water, can taste “flat.” Conversely, a moderate TDS level provides a distinct, preferred taste due to the presence of minerals.
The true health difference lies in the specific electrolytes and mineral content contributing to the TDS measurement. Essential minerals such as calcium, magnesium, and potassium are present in varying amounts depending on the water’s geological journey. Calcium and magnesium are associated with bone health and muscle function, and water serves as a source of these elements, especially in mineral and spring varieties. Consumers interested in mineral intake should look for brands that disclose the specific concentrations of these beneficial compounds.
Packaging Risks and Contaminant Exposure
The container itself introduces potential health concerns related to microplastics and chemical leaching, regardless of the water’s initial quality.
Microplastics, tiny plastic particles less than five millimeters in size, have been detected in most bottled water samples. Contamination often originates from the packaging, the bottle cap, or the bottling process. While these particles are ubiquitous, their long-term health effects are still under investigation, making their presence a growing consumer concern.
Chemical leaching is a risk, particularly from polyethylene terephthalate (PET) plastic bottles, the most common type used. When plastic bottles are exposed to heat, such as being left in a hot car, the migration of chemicals like antimony (used in PET production) and Bisphenol A (BPA) can be accelerated. Glass and boxed water alternatives mitigate these leaching risks, offering a cleaner delivery system for consumers prioritizing purity.
Consumers should also consider emerging contaminants, such as per- and polyfluoroalkyl substances (PFAS) and heavy metals, which can exist in any water source. These substances are persistent in the environment. While purified water tends to have lower levels due to aggressive filtration, spring and artesian sources are not immune. Choosing brands that voluntarily engage in third-party testing for these specific contaminants provides an extra layer of assurance.
Comparative Analysis of Popular Brands
Applying these criteria to popular brands reveals a spectrum of quality driven by source and processing.
Purified Water
Brands like Dasani and Aquafina are purified waters, starting with municipal sources and using reverse osmosis to achieve a very low TDS (often 0 to 10 mg/L). This process ensures high purity and freedom from contaminants. They are an excellent choice for consumers who prioritize the removal of all dissolved solids, but they offer no mineral benefit.
Mineral and Spring Water
Brands like Evian and Fiji are natural spring or artesian waters with moderate mineral content. Evian, sourced from the French Alps, has a TDS of about 357 mg/L, with significant calcium (around 80 mg/L) and magnesium (around 26 mg/L). Fiji Water, from an artesian aquifer, features a TDS of approximately 222 mg/L and is notable for its high silica content, which contributes to its soft mouthfeel. These are ideal for those seeking naturally occurring minerals.
San Pellegrino, a sparkling mineral water, has a much higher TDS, often exceeding 1,100 mg/L. It provides substantial sulfate, calcium, and magnesium, making it a functional source of dietary minerals.
Specialized Water
For consumers interested in alkaline water, Essentia is a popular choice. It is purified water that has electrolytes added for taste and is then ionized to achieve a high pH of 9.5 or greater.
Ultimately, the “healthiest” bottled water is highly individualized. Those seeking purity and ultra-low TDS should choose purified brands. Those prioritizing mineral content for taste and supplementation should opt for high-TDS mineral or artesian spring waters, ideally packaged in glass to minimize leaching risks.