Reverse osmosis (RO) desalination is an energy-intensive process, with centrifugal pumps and their electric drives constituting a significant portion of total system power consumption. Accurate estimation of this energy demand during the design phase is critical for optimizing plant efficiency and operational costs. Existing models often overlook or simplify the contribution of electric drive losses, leading to less precise power consumption projections. This study presents a comprehensive Simulink-based model designed to estimate the total power consumption and efficiency of a centrifugal pump system within an RO desalination plant. The model integrates several key components, including an electric drive loss estimation module, a centrifugal pump, a pipeline network, a pressure regulation valve, a fluid reservoir, and the RO system, within a unified simulation environment. A defining feature of this work is the explicit inclusion of electric drive losses, which enables a more holistic and accurate calculation of overall system efficiency and power demand compared to models focused solely on hydraulic power. By simulating system performance, the model demonstrates its utility as a predictive tool. This allows us to optimize pump selection and control strategies at the early design stage, potentially leading to more energy-efficient and cost-effective RO desalination systems.