Potential Water and Energy Savings for Reducing Urban Water Supply Loss in China

The high water loss rate of the urban water supply system owing to the old and failing water supply pipe network may cause serious water leakage and consequently unnecessary energy waste. Taking water-scarce China as an example, we evaluated urban water loss and the accompanying electricity waste from the water supply network for 266 Chinese cities in 2015 and further designed different water loss control scenarios to assess the potential water and energy benefits in 2035. Results indicated that the quantity of water loss equaled the domestic water demand of 134.0 million urban residents, and the related electricity waste could meet the electricity demand of 4.4 million urban residents for a year. The potential water and energy savings in 2035 can reach up to 4.8–9.7 billion cubic meters and 1.7–3.3 TW·h in different scenarios, respectively. Cities with water scarcity show higher water loss rate, more electricity waste, and greater potential of water and energy savings compared with the others. For water-receiving cities along the South to North Water Transfer Project, the ratio of their total urban water loss to their total water transferred was as high as 70.9% in 2015, and potential water saving can be accounted for 0.2–44.1% of their total water transferred in 2035. We suggested that differentiated local water loss control can be an effective supplement to local water supply and water stress alleviation, as well as energy conservation.