Around 90 percent of the water table under China's major cities is polluted to some extent, with residents of the worst-affected areas forced to buy drinking water, according to a recent official report.
And subterranean water reserves in nearly one-half of China's towns and cities fall short of national safety standards for drinking water, the report says.
This means that the drinking water supply for around 190 million people has excessive pollution levels, according to a joint strategic report on the environment published by China's State Environmental Protection Agency and the Chinese Academy of Engineering.
"China's aquifers are over-exploited and seriously polluted," the report said. "Around 54 percent of the water table in flat regions of China does not meet standards for drinking water."
It said more than 50 Chinese cities had reported serious damage from subsidence, while 25 percent of underground water reserves nationwide are polluted.
It said 64 percent of underground drinking water reserves in 118 major Chinese cities is "seriously polluted."
Corruption blamed
Jiangsu-based environmentalist Wu Lihong, who served a three-year jail term for reporting on pollution levels in central China's Taihu lake, blamed official corruption.
"China has sound environmental policies and good laws," Wu said. "But implementing them properly brings us to a single phrase: official corruption."
Wu said that enterprises routinely bribe local officials in order to cut corners in pollution management.
"The government has created a sort of black market GDP, which takes no account of the environment," he said.
Wu said there is only one way to improve China's level of environmental protection in line with national law and central government policy.
"Controls need to be implemented where standards aren't being met, and enterprises that won't be controlled must be shut down," he said.
An official who answered the phone at the Yuanshi country environmental protection bureau in the central province of Hebei declined to comment on the report.
"I'm sorry, I don't really know about this," the official said. "Our leaders have just gone into a meeting."
'Horrifying results'
An official who answered the phone at the Hebei provincial environmental protection department said the department would look into any reports of illegal pollution.
"If anyone reported such a case to us, then we would investigate," the official said.
Wu said that villages throughout the "rice and fish belt" of Jiangsu and Zhejiang provinces have suffered health problems from polluted drinking water.
"The State Environment Protection Agency brought an American doctor of chemistry to test the waste water at one chemical plant which had already passed environmental tests and was said to be drinkable," he said.
"The results were truly horrifying. The water contained carcinogenic and toxic substances ... After that the factory was shut down."
He said the villagers had resorted to drinking reservoir water which they had bought and shipped in from elsewhere.
'Unbalanced' ecology
Officials and activists warned last month that the ecology of China's lakes and rivers has already become unbalanced, creating major challenges for policymakers.
Deputy water resources minister Hu Siyi warned that China is now swinging between the extremes of "too much" water during flood seasons, and "not enough" water, largely due to rapid economic growth.
He said that problems of water quality, erosion, and a deteriorating ecosystem are accelerating, with no fundamental changes taking place.
Activists say that in the poorest, most heavily polluted areas, water treatment facilities exist but often don't operate to specification, producing poor results.
They have called for the ecosystems of China's lakes and rivers to be built into a model for a greener GDP.
Reported by Fang Yuan for RFA's Mandarin service. Translated and written in English by Luisetta Mudie.