In the present study the involvement of human activities is assessed in the revalorization of groundwater quality. The groundwater quality was assessed on the basis of physical and chemical analysis (electric conductivity, pH, total dissolved solids (TDS), total hardness, NO3-, NO2-, SO4-2, Fe, Mn, Zn, Cu, B, residual sodium absorption (RSC) and sodium absorption ratio (SAR) for the period 2000-2004. From the analysis of results, it emerges that there are significant differences on the quality of water among the sample areas studied. The degradation of groundwater quality is mainly due to the pollution caused by the rural use of land, as well as its intensive exploitation. The salination and toxicity are potential problems of groundwater quality, especially in some areas, indicating that there is a need to take direct actions for the purpose of the optimum management of water resources in the Region of Thessaly.