This paper presents results of an assessment of dominant hydro-geochemical processes controlling groundwater chemical composition, using an integrated application of cluster analysis and factor analysis. The area is located in south of saline playa and in Arak city. Cluster analysis classified samples into two main clusters according to their dominant chemical composition: cluster A (dominant composition: Ca, Cl and SO4) and cluster B (dominant composition: Ca–HCO3). These clusters were in turn described by factor analysis. Results of factor analysis and geochemical interpretation suggest that spatial variation of groundwater quality in the area is influenced by different processes: Analyses revealed three major sources of variation in groundwater composition: carbonat and silicate mineral weathering, saltwater intrusion and anthropogenic contamination. Factor 1 shows processes of dissolution of C and SO4 evaporative salts (for samples close to Arak playa). Factor 2 exhibits strong positive correlation in Zn and Cu and show anthropogenic or industrial sources. Factor 3 exhibits HCO3 and NO3 and is resulted from weathering of carbonate and silicat minerals by percolating water and disposal of domestic wastes.