Drinking water is a fundamental resource for the sustainability of life on Earth, so the preservation and efficient management of this resource are essential. However, due to the constant increase in population and urban expansion together with climate change, the consumption of drinking water has constantly increased; on the other hand, its availability is lower. It is in this context that the use of rainwater emerges, standing out due to being a sustainable, simple, and effective option, where it becomes possible to use water harvested from precipitation, using it for purposes that do not require the level of filtration and treatment of drinking water, such as the irrigation of green spaces, thus contributing to the reduction in the consumption of this resource. Therefore, the main objective of this work was to study and develop a pilot rainwater harvesting system, using as the study area Building 1 of the University of Algarve, on the Gambelas Campus. It was also decided to carry out a comparative analysis, thus comparing the results obtained in the analysis of this work with those of national and international example cases, in order to verify the efficiency of this system. It was thus verified through the analysis of the results that Gambelas has a typical Mediterranean climate, noting a scarcity of precipitation between June and September. It was also verified that with the amount of rainwater possibly stored, reaching 623 658 l or 623.658 m3, it would be sufficient to meet the estimated demand, reaching 441.36 m3. It is therefore concluded that the installation of the proposed rainwater harvesting system would effectively and sustainably meet the water demand for irrigation of the green spaces in the courtyard of Building 1 and its surroundings, thus making use of rainwater and reducing the consumption of drinking water.