The modern water aisle features numerous specialty beverages, often leading to confusion. Alkaline water and mineral water are often confused, but they are defined by different physical and chemical properties. This distinction centers on the concentration of dissolved solids versus the water’s potential for hydrogen, or pH level.
What Makes Water Mineral Water
Mineral water is defined primarily by its source and its content of Total Dissolved Solids (TDS). It must originate from a geologically protected underground source, such as a spring or borehole. The defining characteristic is a minimum concentration of 250 parts per million (ppm) of TDS, including naturally occurring minerals like calcium, magnesium, and sodium. These minerals must come exclusively from the natural source; no minerals can be added later to meet the TDS requirement. The water’s pH level is not a defining factor for mineral water, as it can be neutral, acidic, or basic depending on the source geology.
What Makes Water Alkaline Water
Alkaline water is defined solely by its pH level, which must be greater than 7.0. Most commercially available alkaline waters have a pH between 8.0 and 9.5. This higher pH results from the presence of alkaline minerals like calcium, potassium, and magnesium, or through artificial manipulation. Water can become naturally alkaline by passing over rocks and soil, which releases alkaline compounds. However, much bottled alkaline water is produced through electrolysis or ionization. This method uses an electrical current to separate the water into acidic and alkaline streams, artificially creating the desired high pH.
Compositional Differences and Regulatory Classifications
The fundamental difference lies in their defining metrics and processing methods. Mineral water is defined by its “what”—the stable, natural quantity of Total Dissolved Solids (TDS)—and its protected underground source. Alkaline water is defined by its “how”—the pH level—which can be achieved naturally or through industrial processing.
In terms of regulation, mineral water has a strict standard of identity enforced by the Food and Drug Administration (FDA). This mandates source protection and the minimum TDS content. If a water brand is labeled “mineral water,” it must adhere to these natural sourcing and composition rules. Alkaline water, especially when artificially produced, is often classified as “purified water” or “bottled water” unless it meets the TDS threshold for mineral water.
There is a small area of overlap where water can be both mineral and naturally alkaline, sourced from an underground formation that provides both high TDS and elevated pH. However, many commercial alkaline waters do not meet the minimum 250 ppm TDS requirement for mineral water, while many true mineral waters do not reach the high pH levels typical of alkaline products. Therefore, alkaline water is not necessarily mineral water, and mineral water is not necessarily highly alkaline.