A mixture of geothermal waters having high ionic concentration to cold water aquifers is caused to deterioration at irrigation and drinking water quality. The aim of this study is determine spreading and extending of pollution in cold groundwater with the contribution of geothermal waters in the Sandikli (Afyonkarahisar) basin. Hydrochemical facies of the waters is Ca-Mg-HCO3 and Ca-Mg-HCO3-SO4 in cold waters and Na-Ca-SO4-HCO3 in the geothermal waters, respectively. Ca2+ and HCO3 are dominant ions in cold waters, whereas those in geothermal waters are Na+ and SO42-. Shallow groundwaters have low ionic concentrations, while deep circulation waters have high ionic concentrations. The increases of T, EC, Na+, SO42-, Cl-, B, Al, As, Fe, Mn, Ni, F, U and NO3- parameters were determined in the cold groundwaters as locally due to hydrothermal contribution, waterrock interaction and anthropogenic effects in the Sandikli basin. As a related to groundwater usage, there are two different risks in the basin, human health risk (drinking water usage) and environmental risk (irrigation water usage). From the results of hazard index, it is verified that As is the main contaminant, and toxic human risk can be caused by ingestion of water in the basin.