Mineral water is water obtained from rocks. It is often collected from springs or from underground rivers when they emerge from the rocks. Mineral waters are very clean and have no germs in. Because they have been held in rocks for a long time they often contain chemicals that have come from the rocks. This chemicals can give the water an interesting taste. Some mineral waters may be good for health. Because some underground water comes to the surface from very deep layers in the earth, it can also have carbon dioxide gas dissolved in it. This can make the water fizzy.