São Tiago medical spa is an integrated structure in a new Health Tourism Complex, in Penamacor, Portugal, with a recent start of operation, due to the classification of a new natural mineral water in place. That medical spa bases its exploration on the natural mineral water obtained from the Well P1. Thus, to facilitate the preservation of the quality of the resource, natural mineral water, one of the fundamental instruments is the implementation of a Protection Perimeter of Well P1 and its associated aquifer system. In this sense, in this paper, after briefly presenting the basic geoenvironmental aspects that are the base for the elaboration of the Protection Perimeter, the methodology of its elaboration is explained, with the final solution, which constitutes a territory organized by three zones: Immediate Protection Zone, Intermediate Protection Zone and Extended Protection Zone. The official restrictions legally foreseen for those zones are mentioned and the official systematization of the current occupation of the territory is presented, in terms of the Municipal Master Plan (PDM), while emphasizing the potential sources of existing pollution. Finally, some comments are made about the future orientation regarding the occupation of the territory in the interior zones of the Protection Perimeter, so that the new Health Tourism complex, consisting of a medical spa, hotel, and aqualudic spaces, endures in the time, and helps the sustained economic growth of the region.