**4. Conclusions**

This study showed that the higher the water consumption and the higher the rainwater demand, the greater the potential for potable water savings. The potential for potable water savings increases as the roof area and the rainwater demand increase. In houses with low water consumption, the roof area had little influence on the sizing of the lower rainwater tank. In contrast, for higher consumptions, the tank capacity increased with increases in the roof area. In houses with high water consumption, the rainwater harvesting system proved to be economically feasible. In cases with high rainwater demand and small roof areas, the potential for potable water savings was low, but they were still economically feasible.

The rainwater harvesting system was not economically feasible for a low number of residents and/or low water consumption cases. Therefore, implementing a rainwater harvesting system for single-family homes in Blumenau is economically feasible for most cases, including the actual house. However, performing the economic feasibility analysis for each case is recommended.

**Author Contributions:** A.M.F., conceptualization, methodology, formal analysis, data curation, writing—original draft preparation, review and editing; J.K.M., writing—original draft preparation, review and editing; E.G., supervision, conceptualization, methodology, formal analysis, writing—review and editing; L.P.T., supervision; writing—review and editing. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Not applicable.

**Conflicts of Interest:** The authors declare no conflict of interest.
