This work assessed the potable water savings potential for different scenarios in a flat in Florianópolis, Brazil. An uncertainty analysis was also performed to understand which parameters most influenced the results. First, it was necessary to evaluate the water consumption and calculate the water end-uses during a home-office period due to the Coronavirus pandemic. The water end-uses were obtained by monitoring the users’ consumption for sixteen days and compared with the water meter on a daily basis. The results were very close to those measured using the water meter, with an average absolute error of 5.6%. The base consumption was, on average, 249.2 litres per capita per day. With a home-office regime and uninterrupted occupation, the Coronavirus pandemic can be postulated to justify the more intense consumption patterns. Regarding the percentage of non-potable end-uses, an average of 25.8% was obtained. Potable water savings were simulated using the computer programme Netuno, version 4. Seventy scenarios were evaluated, including different rainwater catchment areas and water and rainwater demands. The main results were that the rainwater harvesting through a reduced area, 17.5% of the roof, obtained significant results compared to the simulation with the whole roof, with a potable water savings potential of 16%.