Potable Water Savings Potential Through Rainwater Harvesting in a Brazilian Fitness Centre: A Case Study

Abstract

Water scarcity and rising urban demand pose growing challenges for sustainable water management in Brazil, where over 73 million people may face shortages by 2035. Given this scenario, rainwater utilisation has emerged as a strategic alternative for preserving water resources, helping to reduce potable water consumption and relieving demand on public supply systems. This study aimed to evaluate the potential for potable water savings through the implementation of a rainwater harvesting system in a fitness centre without a swimming pool, located in southern Brazil—a building typology rarely addressed in the literature. Water end-uses were empirically characterised using water flow measurements and questionnaires conducted in an existing facility operated by the same franchise. A daily balance simulation was performed using the Netuno computer programme (Version 4), and an economic feasibility assessment was conducted based on local costs and tariff structures. The results showed that non-potable end-uses represented 24.4% of total water consumption. The rainwater harvesting simulation indicated an ideal tank capacity of 11,000 L, enabling potable water savings of 7.04%. The economic analysis showed an implementation cost of R$13,240.72 and a consequent return on investment of fifteen months. These findings confirm the technical and economic viability of rainwater harvesting systems for fitness centres and highlight the relevance of local conditions in shaping performance and investment returns.