Mineral water is water that has either naturally or artificially added minerals. Many forms of mineral water are also carbonated, which may also be the result of natural processes. Unlike sparkling water, however, mineral water does not have to be carbonated, and is defined by its having over 250 parts per million (ppm) of a mineral substance.

Most water has to be processed to reduce mineral content, and any unwanted bacteria or chemicals. Mineral water, conversely, is usually obtained from a water source rich in some kind of mineral thought to be beneficial to the health. As water sits in contact with minerals, it can, over time, absorb some of the mineral content.

To define whether mineral water can be called such, one evaluates the contents of trace minerals in the evaporation of approximately a liter of water. Most mineral water contains more than one trace mineral in greater or lesser values. Various mineral components vary widely, but might include iron, magnesium, calcium, or zinc, a very short list of the various chemical compounds.

Perrier, for example, is a sparkling mineral water that contains calcium, magnesium, sodium, potassium, chloride, sulphate, fluoride and nitrate. These occur in varying amounts with the highest mineral content, aside from bicarbonate, being calcium. In ¼ of a gallon (a liter bottle), there is about a tenth of an ounce (147.3 mg) of calcium.

Mineral water has often been thought of as healthy to bathe in as well as to drink. Abano Terme near Venice is a naturally occurring hot springs used by the ancient Romans, and still quite popular today. Mineral water in these hot springs included various sodium compounds. It is doubtful that the Romans actually bathed directly in the springs, which average 188.6° F. (87° C.) in temperature.

Abano Terme remains a popular tourist location, with many bathing in pools of the mineral water. Italy has numerous other hot springs and mineral water locations and commercially produces the most bottled mineral water brands, an impressive 585 brands. This is over four times as many brands as are produced by the US.

There are naturally occurring areas of mineral water on all the continents, however not all are equally beneficial. Some minerals are not considered healthy, even in trace amounts. Yet the practice of taking mineral water for the health still remains hugely popular, although some countries, like the US don’t allow the practice of advertising mineral water as a health benefit.

Some spas that market mineral water for health purposes offer only wells of mineral water. The most popular spas offer places to bathe in and water to drink, while other spas may offer only places to bathe in the water. Practices differ depending upon the availability of the source waters and their mineral contents. As well, some tap water in certain countries is high enough in mineral content to be called mineral water. Experts cite Zurich, as having some of the best tasting still mineral waters available directly from the tap.