<unk>  is<unk>  containing<unk> s or other dissolved substances that alter its taste or give it therapeutic value. Salts, sulfur compounds, and gases are among the substances that can be dissolved in the<unk> .<unk>  can often be effervescent.<unk>  can be prepared or can occur naturally.
Traditionally<unk> s would be used or consumed at their source, often referred to as taking the<unk> s or taking the cure, and such sites were referred to as spas, baths or wells. Spa would be used when the<unk>  was consumed and bathed in, bath when the<unk>  was not generally consumed, and well when the<unk>  was not generally bathed in. Often an active tourist centre would grow up around a<unk>  site (even in ancient times; see Bath). Such tourist development resulted in spa towns and hydropathic hotels (often shortened to Hydros).
In modern times, it is far more common for<unk> s to be bottled at source for distributed consumption. Travelling to the<unk>  site for direct access to the<unk>  is now uncommon, and in many cases not possible (because of exclusive commercial ownership rights). There are over 3000 brands of<unk>  available commercially worldwide.
The U.S. FDA classifies<unk>  as<unk>  containing at least 250 parts per million total dissolved solids (TDS), and is also<unk>  coming from a source tapped at one or more bore holes or spring, originating from a geologically and physically protected underground<unk>  source. No<unk> s may be added to this<unk> .
Mineral water
Fluence
Bicarbonate
Heme
Altrose
Phosphorous acid
Fluoride
Saline 