Economic analysis of hybrid rainwater-greywater systems between demand and supply sides based on cooperative theory

Hybrid rainwater-greywater systems (HRGs) are efficient decentralized water reuse systems with a profound potential for conserving water in buildings. However, the economic unfeasibility of HRGs has hindered their implementation. Methods to improve the economic benefits of HRGs have rarely been explored. This study proposes a comprehensive economic analysis based on the cooperative theory to explore the economic potential of HRGs. An HRG on campus in Japan was selected as a case study to evaluate its water-saving performance. The economic feasibility of the HRG was then analyzed based on the life cycle cost model. Finally, considering that the implementation of the HRG weakened the profit of the main water plants, the cooperative feasibility and driving factors between the HRG and main water plants were explored in terms of mutual benefits based on the cooperative theory. The results highlight that the construction costs significantly reduce the economic benefits of HRGs. HRGs have more substantial economic benefits in cooperation than in non-cooperation. In addition, the subsidy of the government for HRGs makes it easier to drive the success of the cooperation. This study not only provides a new idea for improving the economic feasibility of HRGs but also provides policy orientations to the government to promote decentralized water reuse systems.

Automated summary

This study proposes a comprehensive economic analysis based on the cooperative theory to explore the economic potential of hybrid rainwater-greywater systems (HRGs). A case study was conducted on an HRG on campus in Japan to evaluate its water-saving performance and analyze its economic feasibility using a life cycle cost model. The study also explores the cooperative feasibility and driving factors between the HRG and main water plants based on mutual benefits. The results show that HRGs have more substantial economic benefits in cooperation than in non-cooperation, and government subsidies for HRGs facilitate the success of cooperation. This study provides new ideas for improving the economic feasibility of HRGs and policy orientations for promoting decentralized water reuse systems to the government.