Economic feasibility of a rainwater harvesting system in a residential condominium in the Brazilian Midwest

Rainwater undergoes various processes before it is suitable for residential use. Moreover, it needs to be sent to a residential distribution reservoir. We investigated and analysed the economic feasibility of a rainwater harvesting system in residential condominiums in Campo Grande city, in the Brazilian Midwest, based on water catchment techniques associated with adequate treatment for non-potable uses. Five methods were used to calculate the volume of the rainwater storage reservoir. Normal standard residences, with a catchment area of 100 m(2) and four habitants, were considered in this study. The monthly drinking water consumption per residence is 18.25 m(3) and is 146 m(3) for the condominium. The city of Campo Grande has a tropical climate, with 460 mm of mensal precipitation in the rainy season and 0 mm in the dry season. Therefore, the use of rainwater can reduce water scarcity and contribute to drainage reduction, thereby helping urban drainage systems. The implementation cost of the system was reduced by using low-cost alternative methods and ready-to-use equipment. The proposed system is efficient and economically feasible. Furthermore, a return on investment is realised after approximately 3.5 years.