Water saving potential and economic viability assessment of rainwater harvesting system for four different climatic regions in China

Abstract

Rainwater is one of the most promising alternative water sources. However, the financial outcomes of the rainwater harvesting (RWH) systems are not always assured as economic performance of RWH systems vary greatly under different climatic conditions.This paper investigates reliability, water saving and benefit–cost ratio of an RWH system with different storage tanks and under three distinct climatic conditions (i.e., wet, average and dry year) at four cities in China. It was found that for a standard building (1,600 m2 roof having 560 people), the rainwater supply reliability varies significantly (3.85–20.55%) across four cities. It was found that Guangzhou (South China) always achieves the highest reliability, greatest annual water saving and highest benefit–cost ratio under three distinct climate conditions. By contrast, Beijing (North China) is mostly ranked as having the lowest one. These findings are well in line with the historical annual precipitation in these regions. Also, it was found that across these four regions, it was not possible for a RWH system to achieve a benefit–cost ratio higher than 1.0. These findings indicate that the RWH systems in most regions of China are currently economically unfeasible without government subsidies.

Keywords

• benefit–cost ratio
• climate condition
• rainwater harvesting system
• spatial variability
• tank sizes