This project focuses on the design and performance testing of a greenhouse rainwater recycling system, specifically examining its application at Zen Organic Farm in Hong Kong. The study begins with an introduction to the importance of water conservation and the significance of rainwater harvesting, particularly in regions with water scarcity. The project outlines its objectives, which include assessing the efficiency of the existing system and suggesting design improvements. The methodology encompasses site surveys, literature reviews on rainwater harvesting techniques, and data collection methods, including the calculation of rainwater collection potential, demand, and storage capacity. The project analyzes the collected data to evaluate the system's performance and proposes recommendations for enhancing rainwater conservation. The project also includes ethical considerations and suggestions for future research, alongside a comprehensive bibliography and appendices. The project aims to provide insights into sustainable water management practices within agricultural settings.