This final degree project aims to study water as a limited resource. To do that, we will do the analysis of water management in a multi-family dwelling in Barcelona. In the first part of the project we briefly discuss water as necessary and vital to life, its use and treatment throughout history element and finally what is your current situation and future expectations. In the second part of the work will make a study, focused on the architectural level, of the water that is managed in buildings. On the one hand, we speak of the water entering a building; water supply from the network, and rainwater. On the other hand, we study the water resulting from the various activities that take place in the home. We will focus in features, quality and treatment, as well as the regulations that we can find in this area. In the third part of the work we will apply what has been previously investigated a multi-family building in Barcelona for improved management and water saving taking into account the particularities of this building type. First we carry out a study of existing water facilities and then we determine the water consumed in each home for each unit / activity, the water that can get to pick through rainwater harvesting, and finally the volume of water end generated by the building. With these data we will evaluate sustainable improvements to be gained in terms of water management.