The brackish water reverse osmosis (BWRO) desalination plant has operated successfully for around 80,000 h from 2004. Reverse osmosis membrane technology has improved allowing higher salt rejection, permeate water productivity and durability. But when the membranes should be replaced taking into account the energy consumption increase. The aim of this paper is to assess the operating information available and energy consumption to evaluate when it would be appropriate to replace the membranes taking especially into account the long life elements involved. The graphical evolution of feedwater conductivity, permeate conductivity, feed pressure, pressure drop, specific energy consumption (SEC) and the standardization of the permeate flow, salt rejection and SEC are shown. A comparison between specific energy consumption increase due to membrane performance decay, the regularity of chemical cleaning and membrane replacement in terms of costs has been carried out. The results show that the most effective choice for this BWRO desalination plant is not to replace the membranes in the first ten years of operation taking into account the membranes performance and the cost of electricity at the time. (C) 2015 Elsevier B.V. All rights reserved.