Water desalination technology has emerged as a critical area of research, particularly with the advent of more cost-effective alternatives to conventional methods such as reverse osmosis and thermal evaporation. Given the vital importance of water for life and the scarcity of potable water for agriculture and livestock—especially in the Kingdom of Saudi Arabia—the capacitative deionization (CDI) method for removing salt from water is highlighted as the most economical choice compared to other techniques. CDI applies a voltage difference across two porous electrodes to extract salt ions from saline water. This study will investigate water desalination using CDI, utilizing a compact D.C. power source under 5 volts and a standard current of 2 amperes. We will convert waste materials like sunflower seeds, peanut shells, and rice husks into activated carbon through carbonization and chemical activation to improve its pore structure. Critical parameters for desalination, including voltage, flow rate, and total dissolved solids (TDS) concentration, have been established. The initial TDS levels are set at 2000, 1500, 1000, and 500 ppm, with flow rates of 38.2, 16.8, and 9.5 mL/min across various voltage settings of 1.5, 2, and 2.5 volts, applicable to both direct and inverse desalination methods. Results indicate that desalination processes function effectively at a flow rate of 9.5 mL/min, achieving a performance efficiency of 65%, while a voltage of 2.5 volts yields a performance level of 44%.