Water plays an important role in the body. Normal–weight adults need 2.0–2.5 L/day of water for proper hydration, and it is known for centuries that minerals from the water are important for humans and animals. Different minerals are important in different ranges for different organs and functions. Due to the mass–related need for the minerals, they are labeled macro and micro elements, respectively. Weathering of rocks is responsible for most of the minerals appearing in water. The importance of minerals from drinking water have been denied for some time. However, in districts of Norway, high frequencies of softening of bone tissue among domestic animals, later identified as phosphorous-deficient soils and water, was known hundreds of years ago, and parts of China had increased levels of heart failure, nowadays identified as low selenium. In the nineteenth and twentieth centuries, well–off people in Europe went to health resorts to drink their specific water, water chosen with mineral content expected to be good for a specific complaint.