The U.S.
Food and Drug Administration classifies mineral water as water containing at least 250
parts per million total dissolved solids (TDS), originating from a geologically and physically protected underground water source. No minerals may be added to this water. In the
European Union, bottled water may be called mineral water when it is bottled at the source and has undergone minimal treatment. Permitted is the removal of
iron,
manganese,
sulfur and
arsenic through
decantation,
filtration or treatment with
ozone-enriched air, insofar as this treatment does not alter the composition of the water as regards the essential constituents which give it its properties. No additions are permitted except for
carbon dioxide, which may be added, removed or re-introduced by exclusively physical methods. No disinfection treatment is permitted, nor is the addition of any
bacteriostatic agents. The more
calcium and
magnesium ions that are dissolved in water, the
harder it is said to be; water with few dissolved calcium and magnesium ions is described as being
soft. == Health impact ==