The groundwaters within the ophiolite nappes in the southwestern part of Turkey have different physical and geochemical characteristics and are divided into five different groundwater facies. These are (1) Mg-HCO3, (2) Mg-HCO3-CO3, (3) Mg-CO3-HCO3, (4) Na-Ca-Cl-CO3, and (5) Ca-Mg-HCO3. The waters interact with ophiolites, mainly made up of basic-ultrabasic rocks, are characterized by alkaline and hyperalkaline character. Alkaline waters have high Mg, HCO3 contents and Mg/Ca ratio, and hyperalkaline water has high Na, Ca contents, and low Mg/Ca ratio. The waters in the study area formed by the interaction of meteoric waters with variously serpentinized ultramafic rocks under low-temperature conditions. Silicate weathering is the main hydrogeochemical process that plays a role in the chemical composition of water. Mg-HCO3-type groundwaters are produced under open-system conditions with respect to CO2 due to meteoric water-serpentinized peridotite interactions in a shallow environment. Deep-seated groundwaters are Na-Ca-Cl-CO3-type waters with high pH (TN-8 sample with pH 10.72), depleted in terms of Mg due to water-peridotite interaction under closed-system conditions with respect to CO2. Salda Lake with an alkaline character and high Mg and Na content is characterized by high evaporation and hydromagnesite deposition.