Hydrogeochemical areas as background for specific mineral and thermal waters of Spain

The geological survey of Spain (IGME for its acronym in Spanish) has been carrying out research in the field of groundwater, and in particularly on mineral and thermal waters, since its creation in 1849. As a result, a great deal of knowledge about the origin and nature of this resource has been gathered. This knowledge has lead to an improved evaluation of its quantitative and qualitative value. Mineral and thermal waters have a high socioeconomic value due to the remarkable activity of balneary centres and bottled mineral water plants. This resource, apart from strictly medical criteria, has also acquired a deep social and cultural importance. As a result of recent research performed by IGME, 19 hydrogeochemical areas have been defined in Spain, based on the relationship between the geology and the physical and chemical properties of the mineral and thermal waters. More than 2,000 declared or potential mineral and thermal waters were considered, as well as 4,000 physical and chemical analyses. Another output of this long-term research has been the identification of mineral and thermal waters showing geochemical anomalies. Their elevate content of certain substances and/or high temperatures are often indicators of deep underground circulation.