In order to characterize the physicochemical quality of groundwater, and to examine the behavior of factors influencing water chemism in the Tebessa Plain, which is part of a semi-arid region located in the northeast of Algeria, physicochemical analyses were carried out on 32 water samples from the Mio-Plio quaternary water table. In the east of the study region, in the Djebissa area, most of the Triassic formations form a depression made up of masses of gypsiferous clay, where some outcrops of Triassic dolomites appear together with several blocks of carbonate rocks, torn off during the Aptian- Albian age. In the center and to the west of the plain, carbonate formations are represented by a significant layer of limestone marl and marl from the Cretaceous to Tertiary periods. The results obtained showed that the quality of the water is influenced by the heterogeneity of the geological formations. The concentrations of chlorides, sulphates, and sodium are high in the eastern part of the study area, which can be explained by the impact of gypsum formations, confirmed by the Sr²⁺/Ca²⁺ ratio being greater than 3 ‰ for the majority of samples. In the wells of the Tebessa and Ain Chabro areas, the concentrations of calcium, magnesium, and bicarbonates increase due to the predominance of carbonate formations of borders. The use of the statistical tool confirmed the evaporitic origin of the anions, especially in the east of the study region.