The confirmation of groundwater contamination owing to shale-gas extraction in the United States (see Nature 498, 415–416; 2013) should be a wake-up call for China too. With Chinese groundwater resources deteriorating fast and shale-gas exploitation mushrooming, careful drilling operations and continuous monitoring are needed.

China has the world's largest shale-gas reserves. To satisfy growing energy demands and to reduce carbon emissions, China has prioritized 13 provinces for shale-gas exploitation. Four of these are in northern and northwestern China, where groundwater provides about 70% of drinking water. Around 90% of China's shallow groundwater is already polluted, and 37% cannot be treated for use as drinking water (J. Qiu Science 334, 745; 2011).

Crops irrigated by polluted groundwater have been contaminated. For example, 36% of rice grown in Hunan province, one of the 13 shale-gas priority areas, was found to have cadmium levels above those specified by China's food standards regulation (M. Lei et al. Acta Sci. Circumst. 11, 2314–2320; 2010; in Chinese).

Oil-and-gas exploitation has already exacerbated groundwater pollution, and in Henan, another priority province, 81% and 29% of shallow groundwater resources have been contaminated by volatile phenol and cyanide, respectively (Y. M. Wang and J. F. Dang J. Geol. Hazard. Environ. Pres. 11, 271–273; 2000; in Chinese).

Compared to those in the United States, Chinese shale-gas extraction operations are poorly developed. The chances of poor well construction and hence of contamination are higher, and monitoring programmes are largely absent. Energy and water are bottlenecks that will affect China's sustainable development; better coordination between the two sectors is desperately needed.