If though mineral medicinal waters are a story of the remote past, Spanish Spas really begin during the nineteenth century. The spa exists only when its conception turns it into a company (public or private) that commercializes with the water and the necessary services to those who consume it. Confiscation and industrial bourgeoisie favored and led the fashion of taking baths, thus assigning to hydrological science and to the medical corps of baths only part of the complex spa universe. This difficult balance between medicalization and de-medicalization, between owners and the medical corps of baths, was based on a legislation that said that every spa should be directed by a physician of the corps and that it was them and not the owners, who could choose where they wanted to perform their duties. In 1871 the National Association of Spa Owners was created and it devoted great efforts to defend the interests of the owners of the spas as well as to publicize their establishments, without hesitating to incorporate all the contributions that the doctors were discovering with regards to the virtues of its waters.