In the Bucaramanga region the explotation of groundwater has not been developed to a significant level, but at the moment there is a great interest in its use for human and industry supply. Two geomorphology units are distinguished in the Superior Basin of the Lebrija River. Macizo of Santander is formed mainly by metamorphic rocks of the Precambrico with some igneous intrusions, the second system corresponds to the Bucaramanga plateau, these two systems are separated by the Bucaramanga- Santa Marta Fault and equally they are affected by a significant quantity of structural features. This behaviour affects the regional hydrogeology. The precipitation vary between 700 and 2200 mm, being the pluviometric optimum between 1800 and 2200 m.s.n.m. Isotopes stable 18O and 2H and the radio-active isotope 3H were used to establish a conceptual preliminary model that allows to identify the origins and the areas of recharge of the aquifer systems of the region. Three possible recharge areas have been described for the studied area, the first one among 1800 and 2200 m.s.n.m that it would recharge the plateau; a second recharge area among 1300 and 1500 m.s.n.m that it would feed the waters of La Cumbre hill, El Carmen, the limestones of the Diamond formation, and the other bodies of groundwater. Finally a third recharge area among 2300 and 2700 ®.s.n.m that it would evidence a deeper flow which would feed the south area. The results of the tritium help us to identify groundwater at two times, the first one is recent water related with superficial aquifer and the other one is older water related with deep aquifer. In the same form two precipitation behaviors were identified in the region, the first one this related with the orographies precipitation dated along the Macizo of Santander, the second with the convective precipitation dated along the Bucaramanga plateau.