A calculated quantity of mineral salts is added to water to make it fit for drinking, called mineral water.
Drinking water sold in bottles is labelled as mineral water.
Chemically pure water is not fit for drinking. It corrodes the digestive organs.
Hence, after obtaining pure water by the distillation of river water or water from other sources, a calculated quantity of minerals comprising sodium, potassium, calcium, iron, etc. is added to it before packing.