Impact of residential water saving devices on urban water security: A case of Beijing, China

Beijing is a city with severe water shortage, and the rapidly growing economy and population has led to an increasing water demand for households. Thus, water conservation has become the focus of urban water supply and demand management. This study analyzed the impact of water saving devices on urban residential water consumption and water supply security in Beijing. The results show that the popularization of water saving devices brings significant water conservation potential to households in Beijing, with 22% water saving efficiency in 2019. It is predicted that the per capita urban residential water demand of Beijing in 2030 will be 201 lpd (liters per capita per day), but the water consumption may decrease to 163 lpd, 148 lpd or 133 lpd, respectively, in three proposed water saving scenarios (S1 to S3). Compared with water demand, the water saving efficiency was calculated at 19%, 26% and 34%, respectively. Meanwhile, the total urban residential water consumption under the four scenarios in 2030 would be 1.372, 1.242 or 1.113 billion m3, respectively. However, the Comprehensive National Water Resources Plan proposes that urban residential water consumption in 2030 should be limited to 1.12 billion m3. Therefore, only in the enhanced water saving scenario (S3) can the total urban residential water consumption meet the household demand and achieve the goal of security controlling. In addition, this paper analyzes the cost-effectiveness of water saving devices promotion policy and proposes some further measures to ensure the water supply security and develop the water conservation potential in Beijing households.