Implementing urban rainwater harvesting systems: Multiple potential performances, barriers, challenges, solutions, and future perspectives

Implementation of rainwater harvesting systems (RHS) can substantially support sustainable urban development by providing multiple potential benefits. Previous reviews provided valuable insights into specific aspects of RHS. However, a detailed and systematic critical review on diverse aspects of RHS is lacking. Besides, there has been no attempt to highlight how RHS can support to achieve sustainable development goals (SDGs). Therefore, this article attempts to develop a comprehensive critical review to systematically explore and summarize the multiple potential performances of RHS, their barriers, challenges, solutions, and future research directions, especially highlighting how RHS assist in attaining SDGs. The findings demonstrate that multiple potential performances of RHS are influenced by spatiotemporal variation of rainfall, water demands, tank sizes, contributing areas, and occupants. The impacts of climate change on RHS are not only reliant on the extent/trend of climate change, but also on locations, water requirements, and tank sizes of RHS. The current modelling approaches of RHS need to be improved and developed to meet the multi-purpose nature of RHS. The quality of rainwater is affected by local conditions and components of RHS, and a robust treatment is required before using for potable water supply. The capital cost, public perceptions, lack of knowledge about RHS and their potential risks are major barriers for widespread implementation of RHS. It is demonstrated that RHS significantly contribute to directly and indirectly achieving SDGs. Finally, it is recommended to explore how social, scientific/political, and institutional assistance can enhance the effectiveness and acceptance of RHS in future research.