**Francisco Berenguel-Felices \*, Antonio Lara-Galera \* and María Belén Muñoz-Medina**

Escuela Técnica Superior de Ingenieros de Caminos, Canales y Puertos, Universidad Politécnica de Madrid, 28040 Madrid, Spain; mariabelen.munoz@upm.es

**\*** Correspondence: franciscoberenguel@ciccp.es (F.B.-F.); alargal@ciccp.es (A.L.G.)

Received: 4 May 2020; Accepted: 18 June 2020; Published: 23 June 2020

**Abstract:** Population growth has increased in the last two centuries. In the driest countries, water supply alternatives are scarce, and desalination is an alternative to guarantee water supply. The question is what conditions must be met by the new desalination plants to achieve the objectives of sustainability. The present study is an analysis of the social, economic, and environmental variables that are critical in the development of desalination plants: technology used, energy sources, correction of the generated environmental impacts, and the most appropriate contractual model for its development. These attributes justify at the time of writing why reverse osmosis is the safest and most efficient technology among those available and those that are under investigation. It is proposed to incorporate renewable energy production sources, although it is still necessary to continue depending on the significant contribution of the traditional energy sources. The need will also be demonstrated to adopt corrective measures to mitigate against the impact produced on the environment by energy production and to implement monitoring plans to confirm the validity of these corrective measures. Finally, turnkey contracts are proposed because osmosis technology is complex, although technology should be justified by means of a decision support system. One of the determining factors is proposed in this present analysis.

**Keywords:** sustainable development; desalination; reverse osmosis; renewable energies; environmental impacts; decision support systems; types of contract
