Economic feasibility analysis of rainwater harvesting: a case study in Imbituba, Brazil

This paper presents a case study on the economic feasibility analysis of rainwater harvesting in single-family houses located in Imbituba, Brazil. A base case scenario was chosen and 108 scenarios were evaluated considering different roof areas, number of residents, potable water and rainwater demands. All scenarios were assessed by means of computer simulations. The payback period for the base case was 14.8 years, and the internal rate of return was 9.1% per year. As for the scenarios analysed, rainwater harvesting was economically feasible in 57.4% of the cases; payback periods ranged from 9.3 to 19.7 years, and internal rates of return reached 15.3% per year. The scenarios with the best economic feasibility were those with the largest number of residents, roof areas and daily water demand. The main conclusion is that rainwater harvesting in Imbituba and cities with similar characteristics can be economically feasible.