This study aims to assess the quality of groundwater in Grand-Lahou department in southwestern Côte dIvoire and to determine the origin of their mineralization. To do this, a sampling campaign conducted in september 2021 focused on twenty boreholes and nine wells. The methodology is based first on the physico-chemical characterization of these waters through elementary statistics and the determination of their chemical facies using the Piper diagram. Then the multivariate statistical analysis (PCA) is applied to know the origin of the mineralization. The results show that the waters are acidic with pH values ranged from 4.6 to 7.8 with an average of 5.75. Apart from iron, the parameters of the groundwater respect the WHO standards and they are fit for consumption. The groundwater has three chemical facies: the calcic and magnesian bicarbonate facies (31.03%), the sodi-potassium bicarbonate facies (17.24%) and the sodi-potassium chloride facies (51.72%). This plurality of facies highlights the complexity of the geological formations in the area. The mechanisms controlling groundwater mineralization are mineralization-residence time intrusion of brackish water and anthropogenic pollution by surface inputs. This study provides a database for the management of groundwater resources.