The global scarcity of fresh water and the extensive use of Reverse Osmosis (RO) systems for drinking water production necessitates optimizing operational conditions to enhance membrane lifespan and water quality. This study investigates the factors affecting the efficiency of the RO process at the Genaveh Combined Cycle Power Plant to optimize water purification (reducing electrical conductivity). The impact of pressure, temperature, recovery rate, and Total Dissolved Solids (TDS) concentration of feed water on salt rejection and permeate flow rate was examined. Regarding the rate of salt rejection, changes in the concentration of Ca2+, Mg2+, Na+, SO42-, NO3-, and SiO2- ions were investigated and measured using titration methods, an online sodium meter, and a spectrophotometer. Results indicate that feed water pressure significantly influences permeate flow rate, with a linear increase from 27.1 to 32 m³/hr as pressure rises from 10 to 18 bar, peaking at 18 bar. This increase in pressure also enhances salt rejection, as evidenced by the rising ion removal rate. Improving feed water temperature from 17 ͦ C to 35 ͦ C increases permeate flow rate, indicating a direct relationship, while the trend of ion removal decreases with temperature. An increase in the TDS concentration from 710 to 875 ppm results in a decrease in the permeate flow rate. Additionally, a decreasing trend is observed in the percentage change of pure water recovery compared to the permeate flow rate and ion removal. These findings provide valuable insights for optimizing RO system performance in water treatment processes