The population growth in the region of Fez-Meknès (1.6 Million), accentuated by the increasing number of wells for agriculture, and by the increasing aridity in recent years, poses the problem of controlling water of sufficient quality and quantity over time. This fractured karstic Basin mainly composed of Liassic dolomitic limestones overlying Triassic basalts, shales and evaporites, is the main drinking water supply in the region. The karstic reservoir presents a decline in its chemical quality and ponctually some turbidity problems. To better understand this system and the interactions between different aquifers and aquitards, we conducted coupling study on: i) geochemistry (major and minor elements, δ 18 O, δD and 222 Rn) of the main springs of Liassic and Triassic origin that could be connected each other and with the major spring of Bittit; ii) electromagnetic multi-scale tomography for separating draining faults from not draining faults (geological structure). The geochemistry of water during the three surveys in 2009 and 2010 shows a major Liassic origin for Bittit, Ribaa, Aguemguam, Amansayarmine, Bou Youssef and El Hajeb springs, and a major Triassic origin for El Mir, Sbaa, Maarouf1 and Maarouf2 springs. Radon 222 (T=3.85days) has highlighted the existence of areas of rapid exchange between waters of Liassic aquifers characterized by low Radon activity (3500 Bq/m 3) and waters of Triassic aquitards characterized by a high Radon activity (> 12000 Bq/m 3). The transit time from the Triassic aquifer is less than two weeks. Analyses of δ 18 O versus δD show only a slight excess of Deuterium, this characterizes a local recharge of the groundwater. Geophysical measurements of resistivity and conductivity show anomalies in the direction of Bittit and perpendicularly to the Causses, confirming the presence of a preferential drainage where Liassic waters of high quality mix with those in contact with the Triassic aquitard.