Access to potable water is needed for every human. Desalination of seawater is a reliable method to ensure this necessity is provided. As renewable generators are pollution free, they are gaining importance in powering reverse osmosis (RO) plants. Penetration of renewable energy into the desalination industry bought new operational challenges. This manuscript aims at maximizing the renewable energy utilization and reducing the operational cost of an RO desalination plant using unit commitment incorporated with co-operative demand side management (DSM). For the flexible operation of the RO plant, it is proposed to design the system as a number of independent units. Partial operation of RO units is also considered in the present study. The proposed unit commitment with DSM schedules both generators and RO units with minimum operational costs. The proposed method is applied to grid-connected and islanded RO plant. PV, wind turbines, diesel generator, and battery are the generators considered for the study. The results obtained are compared with the conventional unit commitment scheduling algorithm. © 2020 IEEE.