Boron water is a type of medical mineral water. According to the National Medical Hot Mineral Water Quality Standard, water with oxoboric acid concentrations over 50 mg/L and 1.2 mg/L can be used for medical and drinking purposes, respectively. Water labelled as boron water must contain boron over 50 mg/L. In Europe, the standard for natural drinking boron water is 5 mg/L or above. Boron water is common in hot springs around the world. In the Shuimogou hot spring in Urumqi, Xinjiang Province, the boron content is as high as 140.44 mg/L, and the spring has been transformed into a spa and sanatorium for medical and healthcare purposes.