Currently, the shortage of fresh water for human consumption has surpassed the available natural capacities, resulting in rationing and shortages as the global population grows. In response to this issue, the industry has developed various fresh water generation systems, with Reverse Osmosis (RO) standing out due to its high production capacity and low energy consumption. However, the automation and control strategies employed in these systems are often basic, relying primarily on human experience or manual control methods. These approaches are not suitable for managing the complexity of multivariable dynamic systems, which leads to premature wearing of system and its equipment. This work aims to show the performance improvements that advanced multivariable robust control techniques can bring to these systems. To achieve this, we present the design, simulation, and implementation of H-Infinity (H∞) controller for a reverse osmosis plant. The obtained results will be compared with traditional control techniques, such as PID, to highlight improvements in efficiency, performance, and equipment longevity.