The underground water supplies of around 90% of China's cities have been polluted by rapid economic growth, a senior environmental official has said.
Waste discharged into rivers can seep into the underground supply
Zhang Lijun, Deputy Director of the State Environmental Protection Administration, called the problem "serious", the China News Service said.
He said the economy's growth would put enormous pressure on water supplies.
The warning follows last month's large toxic spill into a river in north-east China, which raised health fears.
China's official media said underground water supplies provide drinking water for nearly 70% of China's population and 40% of agricultural irrigation.
Experts at an environmental hearing in Beijing said rapid economic advances over the past two decades was causing heavy pollution and could lead to an ecological and environmental crisis, the news service reported.
"A survey showed that underground water in 90 percent of Chinese cities has been polluted by organic and inorganic pollutants, and there are signs that [it] is spreading," the environmental bureau said.
Mr Lijun added continued economic growth could see China facing an even more severe situation in the next 25 years.
In November, the north-eastern city of Harbin had its running water switched off for five days, after 100 tonnes of benzene spilled into the Songhua river, affecting 3.8m people.