After an analysis on the water scarcity, the dissalation technologies and the renewable energy techonolgies that can be used jointly with them, the problem of modeling a plant that exploits the production of freshwater from saltwater through a Direct Contact Membrane Distillation (DCMD) technology thermally fed by vacuum tube collectors is addressed. A model is developed using Simulink software, and results for the city of Turin are investigated through the help of a sensitivity analysis; an economic analysis based on the estimation of water cost is a supplementary tool for the choosing of the optimal parameters. Optimal configuration is analysed in detail, and insights and minor issues are outlined for further research.