Lately, due to overutilization of scarce natural resources such as water, tourist islands have been severely threatened. This is also the case in Santa Cruz Island, the main inhabited island of the Galápagos Archipelago. Therefore, a Multi-Criteria Decision Analysis (MCDA) was carried out with the aim of mitigating the future water crisis. The proposed solutions were evaluated in terms of environmental, technical, economic and social criteria. The results indicate that the ‘best’ alternative for municipality representatives is the option including desalination. However, for the other two groups of stakeholders, the chosen option was the one that combined all the proposed alternatives (greywater recycling, specific demand reduction and rainwater harvesting), except desalination. Conclusions show that for most stakeholders the environment is the most important criteria.