Achieving long-term sustainability in potable water production is one of the greatest challenges facing countries with an arid climate, such as Kuwait. The socioeconomic environment of the country has created a rare paradox of staggering water consumption and chronic water scarcity. This research formulates a mathematical model that can identify the best policy to produce desalinated water while focusing on ecological and financial indicators. The parameters derived from each indicator are coupled with a weighted normalization scheme to generate a composite sustainability index based on the relative importance of each indicator from a rentier socioeconomic perspective. Seven desalination settings coupled with the available energy options, including fossil-fuel types, solar power and nuclear energy, were compared based on ecological and financial aspects and incorporated into a mathematical model. The ecological aspect was evaluated with a life cycle assessment (LCA), and the financial aspect was calculated using net present value (NPV) formulas with a nominal discount rate. The optimization model was formulated with a mixed integer program (MIP). The optimized policy indicates that two main desalination plants should maintain the Multistage-Flash Desalination while operating on natural gas, the remaining plants should use Multi-Effect Distillation with solar energy.