Assessment of the municipal water cycle in China

- The municipal water cycle was characterized for 655 Chinese cities.
- In > 100 cities in North China, their municipal cycle is exposed to water scarcity.
- The proposed options may technically secure urban water supply toward 2030.
- Better efficiency and cost-effectiveness of the municipal system is to be achieved.

Water produced from municipal utilities accounts for nearly 10% of the sum water demand in China. The municipal water cycle that integrates processes of urban water supply, water use, sewage treatment, and water reclamation has been assessed for 655 cities across nine drainage areas in mainland China in 2012. These cities in total extracted 55 km3 raw water for municipal use from surface waterbodies and ground aquifers, approximate to the countrywide freshwater extraction of Russia or Italy. After purification and transmission, 45 km3 water was distributed to industrial, service, and domestic users. 36 km3 of post-use sewage was collected and environmentally safely treated; merely 3.2 km3 of the treated water was reclaimed. Driven by increasing urbanization, the municipal water demand in cities of China may grow 70% by 2030. The Hai River and the Huai River basins, which harbor 137 cities and occupy a majority of the densely populated North China Plain, are most exposed to physical water scarcity. The municipal water abstraction in these cities can remain constant by promoting demand-side and process conservation in the next two decades. Interbasin transfer and unconventional sources will provide municipal water double than the cities' need. Whereas the urban water security can be technically enhanced, the challenges are to better improve water use efficiency and mitigate economic and environmental costs of the municipal system.

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