Financial potential analysis of rooftop rainwater harvesting systems in different regions of China

Abstract To assess the financial viability of rooftop rainwater harvesting (RWH) systems nationwide, simulations were conducted on the financial performance of the proposed RWH system for 59 sample buildings in 36 cities across China. An innovative indicator, namely catchment fraction, has been introduced to evaluate the financial efficiency of the RWH systems. The minimum recommended catchment fractions were derived for each city. A graphical representation of the economic potential of different cities and an isopleth map dividing mainland China into 10 sub‐regions based on threshold catchment fractions were created to facilitate practical application. The results indicate that implementing RWH systems can be economically viable in buildings with catchment fractions exceeding the city‐specific recommended values. These findings aid investors and owners in making informed decisions regarding RWH projects and provide valuable insights for water‐related authorities to formulate legislation encouraging the adoption of the RWH system in China.