Water scarcity is severely high in the North Africa and the Middle East (MENA) regions. The deterioration of water quality has an impact on the human health as well as on the development of agricultural activities, especially in arid regions, where precipitations are less frequent. The aim of this work is to identify and evaluate the chemistry of the groundwater aquifer in the region of Messaad plateau. This region is located 370 km south of Algiers in southern Algeria. A dozen of samples were collected from wells and analyzed using physic-chemical technics, and the results were processed statistically. The distribution of the conductivity values and the various chemical parameters suggest that the groundwater in the Messad wadi area is overall highly mineralized, with the EC ranging from 550 µS . cm–1 to 8790.13 µS . cm–1, with a predominance of calcium sulphate facies and calcium chloride facies. The level of mineralization noted in the southern and southeastern portions of the research area sheds light on the source of natural contamination. The SO42–, Cl– , Ca2+ , Na+ ions are the most important factors influencing the electrical conductivity of water and the groundwater chemistry. These ions are the result of the continuous dissolution of gypsum and halite in the clays and marls of the Barremian formations.