A reverse osmosis (RO) seawater desalination system has many advantages such as saving energy and using less installation space, and has become regular technology to obtain fresh water from seawater. A significant way to lower energy and installation space is to raise system recovery, and we have developed anew RO seawater desalination system which provides 60% recovery of fresh water for 3.5% seawater. The new technology is called a brine conversion two-stage SWRO system (BCS). This system includes several new technologies such as system configuration, energy recovery, operating condition, etc.; high-performance membrane technology; anti-biofouling technology and a new analysis method. A pilot plant has been operated successfully at Toray's Ehime plant site since 1997. The first commercial plant of 4500m(3)/d (1.2mgd) has been operating successfully since March 1999 in Mas Palomas (Gran Canaria, Spain). The Tortola and Curacao plants in the Caribbean have been installed with the fall BCS (first- + second-stage RO system), and also operated under good conditions. A new application of the BCS, installed at the Muroto plant in Japan, has been in operation to obtain bottled drinking water and high concentrated mineralized water from deep seawater. Furthermore, other plants are under construction in Spain and the Caribbean. The BCS is presumed to be the standard SWRO system for the 21st century.