A combined solar thermal water distillation and energy co-generation system has been proposed as a potential solution for decentralized applications in support of the United Nations Sustainable Development Goals. This project aims to assist with the proof of concept of the system by developing a simulation model of a pilot system (~6kW thermal). The system comprises of an indirect solar thermal collector loop (compound parabolic collectors), which provides heat to a helical coil boiler where steam is produced at ~ 1atm using contaminated feedwater (e.g. saline). The steam is expanded in a steam expansion engine to produce mechanical work which can be used directly for pumping or converted to electricity. The saturated vapour leaving the engine is condensed and the distilled water is collected for later use. The model of the system was developed in Flownex SE and allows for the prediction of the system performance as a function of transient solar and ambient conditions. On a sunny summer's day with a solar irradiance of 6.04 kWh/m²/day, the system is predicted to produce 68.6 L of water and 1.08 kWh of mechanical energy at a specific energy consumption of 725.1 kWh/m³. Annually, the system is expected to produce 17706 L (~1100 L/m² of collector area) and 287.2 kWh (17.7 kWh/m²) of distillate and mechanical energy respectively. The system proves to be too inefficient to compete with more established technologies such as solar photovoltaic reverse osmosis.