Introduction From the very beginning，main target in the Desalination Industry R&D has been to improve the SWRO plants efficiency in order to reduce the cost of the desalted water．These efforts have been mainly focused on the energy recovery devices(Francis and Pelton Turbines，Turbochargers，Isobaric Chambers)and the Membrane elements，as they have been traditionally the areas where better improvements were achievable．Nowadays desalted water cost reductions are becoming slighter day by day，but they are still cost effective since Desalination plants sizes are also becoming bigger and small efficiency increases produce important OPEX saving．However these small efficiency increases can be obtained also by focussing in other plant elements as Centrifugal Pumps，more particularly their design and selection．