Thermal water has been identified as hot water with the composition rich in salts, iodine and gases. It appears from natural thermal areas common throughout the earth and in fact on each continent, even in the oceans. In fact, ground water is heated by geothermal processes and flows naturally to the ground surface at a temperature of 70 °F (about 21 °C) or higher.
Geothermal baths can be found in places where magma is close to the surface, especially in a hot spot and volcanic regions or propagating mountain ridge.
The origin of many heat sources can be found in aquifers which are underground layers of rock and sand that contain water. Thermal water can also occur from artesian wells.
Thermal water in the region of Gastein (Austria) comes from a natural source of Florentine Hill. This is water rich in natural chloride that appears out of the depth of 1200 - 1 800 m, and goes through solid rock to the surface. Its temperature is between 56 °C and 68,8 °C, and the source performance is approximately 800,000 liters of thermal water.
Examination showed that rainwater seeps into the area of thermal waters (approximately 1,800 meters above sea level), after they go to a depth of 2,000 meters. This water is warmed deeply beneath the earth, and rises about 1,000 meters above sea level. This unique water is successfully used in SPA procedures and during treatment.