The objective of this paper is to analyse the economic feasibility of using rainwater for non-potable purposes in single-family houses in the city of Blumenau, Brazil. A house was used as a case study to estimate the water end-uses and water consumption. Residents were asked to register the frequency and time of use of water fixtures. Then, the daily water consumption and water end-uses for non-potable purposes were estimated. To account for houses of different characteristics in Blumenau, different roof areas, number of residents, daily per capita water consumption, and rainwater demand were adopted. The rainwater tank capacities, the potential for potable water savings and economic feasibility analysis were performed using the computer programme Netuno 4. For the different scenarios, the potential for potable water savings ranged from 18.76% to 58.06%, with an average equal to 37.90%. For the case-study house, the potential for potable water savings was 50.32%. The rainwater harvesting system was found to be economically feasible for 58.3% of the different scenarios and also for the case-study house. Thus, the implementation of rainwater harvesting systems for single-family houses in Blumenau proved to be economically feasible for most cases.