Several important lessons were learned during the design and implementation of the brackish groundwater desalination best practice in Matrouh. Early integration of site-specific hydrogeological conditions into the system design was essential to ensure optimal well selection, pump sizing, and treatment efficiency. Proper pre-treatment design proved critical to protect reverse osmosis (RO) membranes and reduce operational problems such as fouling and scaling. The integration of photovoltaic (PV) solar energy highlighted the importance of accurately matching energy demand with solar supply to ensure system stability. It was also learned that involving local stakeholders and operators from the early stages of implementation improves acceptance, operational efficiency, and long-term sustainability. In addition, logistical planning for equipment installation in remote desert areas is a key factor affecting project timelines and costs. Overall, adaptive design and local capacity building were identified as key success factors for effective implementation.