The demand of water is increasing day by day because of population explosion and rapid urbanisation. In this regard, desalination is one of the prominent technologies for providing potable water from saline aqueous media. Among available methods of desalination, seawater reverse osmosis is commercially viable and practiced in many countries of the world. But high energy use is one of the drawbacks of reverse osmosis process. Hence, this study aimed to analyse flow energy of reverse osmosis unit in seawater desalination plant with energy recovery device. A conventional material and energy balances is applied for the analysis. From the analysis, zero loss is observed in recirculation pump and significant loss of 66.65 kJ/s is estimated in energy recovery device. It could be concluded that energy recovery device is a suitable option to reduce the energy use in reverse osmosis unit.