Benefit evaluation of reclaimed water utilization in megacities: Multidimensional evaluation framework and case study

Reclaimed water utilization is a crucial approach to addressing urban water scarcity, and a scientific assessment of its benefits is essential for promoting the sustainable development of this sector. However, existing studies still exhibit limitations in the comprehensiveness of evaluation frameworks and their specificity for the megacity scale. To address these gaps, this study developed a multidimensional evaluation framework for reclaimed water utilization benefits based on China's guidelines and megacity characteristics. This framework encompasses resource, environmental, and social benefits, and quantifies them into economic values for integrated analysis and comparison. It not only allows for accurate status evaluation of reclaimed water utilization but also provides a forward-looking basis for reclaimed water industry planning, serving as a reliable and operable decision-analysis method for water management in megacities. The framework was applied to a case study of Beijing, China in 2022. The evaluation quantified the significant value of reclaimed water utilization at 14.77∼15.42 billion CNY (2.09∼2.18 billion EUR), while also revealed common systemic challenges, such as limited application diversity and the coexistence of energy consumption and health risks. Accordingly, this study further proposes targeted policy recommendations, including: promoting diversified application scenarios, strengthening technological innovation and risk prevention, building a full-industry-chain support system, and establishing a multidimensional public participation mechanism. The research outcomes provide a instructive methodology and strategic insights for guiding reclaimed water planning and sustainable urban water management in megacities globally.