A small scale solar powered desalination system has been designed, analyzed, and optimized with regard to power needs and energy consumption. Both quantities scale linearly with the concentration of the total dissolved salt concentration (TDS) in the feed solution. The desalination of brackish water at a TDS value of 3,000 ppm requires an energy of approximately 1.5 kWh/m(3). For seawater at a TDS value of 34,000 ppm, this value increases to 9.5 kWh/m(3). The selected type of membrane, the system design, and, in particular, the efficiency of the high pressure pump crucially affect energy consumption. The desalination cost also has been estimated for a small scale system that linearly scale with the TDS value of the feed water. [S0199-6231(00)00104-0].