This work is being developed in the district of Pecém (Brazil) in a region included in the so called Polygon of Droughts, which presents a pluviometric regime marked by extreme irregularity of rains, in time and space. In this scenario, water constitutes a natural asset with a high limitation on the socioeconomic development of the region and even on the subsistence of the population. The objective of this work is to identify the quality of the groundwater, the salinization processes and the efficiency recharge of the aquifer, using isotope measurements of Oxygen-18 and Deuterium, physical and chemical analysis and measurements of concentration of the major ions, in a set of samples collected in 33 tubular wells, belonging to the Ceará Water Resources Management Company (COGERH) sampled in two collections. The pH measurements reveal acid waters with values of up to 6.0 and most of the hydrochemical data show waters chemically suitable for human consumption. The results of the electrical conductivity measurements show values lower than 800 μS/cm in 31 of the 33 wells sampled; the highest values were 826 and 1125 μS/cm, characteristic of waters with high salinity. The concentrations of the cations and anions of the largest elements present in the water, in the two collections, indicated waters of the sodium chlorite type in most of them. The average values of electrical conductivity in the first collection 434 μS/cm and in the second collection 260 μS/cm show dilution process in the groundwater caused by the recharge with rainwater also indicated by the pH values. The relations δ18O - δD evidence evaporation processes.