Rainwater is one of the most promising alternative water sources. However, the financial outcomes of the rainwater harvesting systems are not always assured due to the economic performance of RWH system varies greatly under different climatic conditions.This paper investigates reliability,water saving and benefit cost ratio of 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 is 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 is found that Guangzhou (South China) is always achieving the highest reliability, greatest annual water saving and highest benefit cost ratio under three distinct climate conditions. In the contrary, 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 is found that across these four regions, it is not possible for a RWH system to achieve benefit cost ratio higher than 1.0. These findings indicate that the RWH systems in most regions of China is currently economically unfeasible without government subsidies.