Produced by ICRA and LEITAT The objective of this deliverable is to propose a preliminary design of the decision support system (DSS) that will be used to determine the environmental, economic, and social impacts of the installation/incorporation of water-saving and/or water-reuse technologies and practices in hotels.This document is aimed towards the consortium partners of the demEAUmed project, which will provide information on the life cycle as well as their technologies operation for their subsequent incorporation in the DSS. This document will begin with a preliminary design of the DSS, followed by the summary of the existing research on water use in hotels, as well as existing water cycle models.Then, using one of the existing water cycle models, a simulation of hotel water use will be summarized to determine the impact of water use technologies on potable water use. Next, the incorporation of a technology library will be explained as well as the progress on its information gathering.