Desalination has been used for thousands of years. Today’s sophisticated methods still generally use the concepts of distillation or filtration including Membrane Systems. The biggest plants are generally in United Arab Emirates and Saudi Arabia. Saudi Arabia has some the largest desalination facilities in the world including the Shoaiba complex, producing over 880 million liters per day. In this talk, desalination history, application of membranes in water & wastewater, will be reviewed. This review will focus on water quality and energy consumption as well. This depends on several factors including, but not limited to, desalination technique, TDS concentration and temperature of source water (feedwater), plant capacity, and the plant location with respect to the source water intake and the concentrate discharge. From a water-energy nexus perspective, three approaches, collocated plants, cogeneration plants and hybrid plant, provide opportunities for energy use efficiency in desalination plants.