It is generally accepted that Israel and its neighboring countries will be, in the next decade, dependent on large seawater desalination plants. The preferred technology will, most probably, be SWRO. In this technology, a major design problem is the inferior physical, chemical and microbiological seawater quality, especially on the Eastern Mediterranean shore. Recent developments in the field of water treatment, holding a promising potential to facilitate desalination of low quality raw water, and to reduce the cost of desalination, are the new technologies of membrane processes such as micro- and ultrafiltration. These new backwashable capillary technologies, recently commercially introduced, can dramatically improve the quality of surface seawater. This is especially important if cooling water from existing power-stations is used as feedwater for SWRO plants. This option enables shortening the time period needed for construction of large desalination plants and reducing the cost, in comparison with conventional design options. Comparative design options of a 150,000 m(3)/d SWRO plants, recently investigated by Mekorot, are presented. The preferred option, based on UF treated cooling water fr om power-station, indicates the lowest desalinated water cost, within the range of US$0.50/m(3).