In two previous papers published at the 2003 IDA Conference and the 2004 EDS Conference, different energy recovery systems were analysed with respect to their overall life-cycle costs. The core hydraulic system with a pressure exchanger was identified as the most advantageous ERS concept, and the question of appropriate component design and system optimisation was discussed. As a result, the advanced SaITec core hydraulic system was designed. Since May 2004, this system has been installed in a seawater reverse osmosis (SWRO) plant in Sharm El Sheikh (Egypt) and tested under field test conditions. The outcome of the field tests has been reported in two further papers published at the 2005 EDS and IDA Conferences. Reflecting these results, the approved SalTec technology was extended to handle higher flow rates (up to 5000 m(3)/d) with reduced specific energy consumption. In the current paper, the design of the extended SalTec system, especially the new size of the SalTec DT pressure exchanger, is described in detail. Results of the performance tests (leakage, pressure losses, mixing) are reported.