Spatiotemporal characteristics analysis of water saving potential and economic effectiveness of rainwater harvesting system in China

Financial viability of rainwater harvesting (RWH) system is highly determined by regional conditions such as rainfall pattern and water prices. Successful implementation of rainwater harvesting systems depends largely on the identification of suitable sites. This paper presents the water saving potential and economic effectiveness of rainwater harvesting systems across eight major cities in China, using a daily water balance model. Results show 6 to 81 days (or 1.6 to 22.2%) of dependability can be achieved by using a rainwater harvesting system over these cities. The annual water saving efficiency ranges from 10% to 37% and the benefit cost ratio varies between 0.45 and 1.20 across the studied cities. South China achieves the maximum annual water saving and the uppermost benefit cost ratio, while southeast China has the most habitual summary of precipitation use. Northwest China was found to be the region with the worst performance, both in yearly water saving and in regularity of rainwater use on a yearly scale. It was also found that the RWH system is not financially feasibility in the northeast, southwest and Central Plains due to the benefit-cost ratios being smaller than 1.0.