Water is the most important natural resource for society, due to its economical, strategical and social value, being vital for life on the planet. As a renewable good, it must be managed in a conscious way, once it may become scarce. With population growth and the development of economies, there is a tendency for the enhancement of its demand. In a survey carried out by the United Nations - UN (2018), this increase varies around 20 percent to 30 percent, that is, 4600km cubic/ year until 2050. In Brazil, the lack of water peaked in 2014, but it is recurrent in the country s large urban centers. As well as in the Northeast region due to climatic and meteorological aspects. Therefore, the rainwater utilization arises as a response for the problems of the impacts caused by the lack of water in large urban centers. This form of treatment would minimize the use of water sources, the cost of water treatment, the impacts of floods and the costs of the population with water bills. With the use of rainwater being implemented in condominiums, the perspective is to reduce the demand for treated water. As a result, lower water bill payments and, thus, reducing the impact of the population s cost of living. A and not less important, to reduce the pressure on the demand of the companies and to smooth the withdrawal of water resources from the environment. As a goal, the research analyzed the system to be implemented, its cost and economic viability in buildings already constructed. In urban centers, there is a demographic density already established, which demands a large amount of water, and also consolidated buildings that aggravate the impact of water scarcity. To achieve this objective, this research simulated the implementation of a rainwater recovery system, considering three reservoir alternatives. Then, a case study was carried out in the Park Riviera da Costa condominium, in the city of Rio de Janeiro, in the neighborhood of Campo Grande, using indicators such as Present Value (VP), Net Present Value (NPV), the Internal Rate of Return (IRR), Profitability Index (IPV) and simple payback.