A survey by China's Environmental Protection Administration says underground water supplies in 90 percent of Chinese cities are polluted, raising concerns about the safety of drinking water for the country.

The contamination in China's water supplies is caused by fast-paced economic growth, with increasing amounts of industrial waste from factories and untreated human waste discharged into rivers.

The survey, reported Wednesday in the Chinese media, says underground water supplies provide drinking water for nearly three quarters of China's population, as well as irrigation for about 40 percent of the nation's farmland.

Kevin May works for the environmental organization Greenpeace in China's southern city of Guangzhou. He says it is urgent that existing laws be enforced to prevent the problem from getting even worse.

"Actually in China, when you study closely, there are legal standards, there are legislations preventing water pollution as well as other kinds of pollution like air and soil," he said. "But we can see the problem at local level, that these standards and legislations are not fully respected and not abided by by the local governments and the industrial sector - this is really worrying."

But Mr. May says it is a positive step for the Chinese government to admit the seriousness of the country's water pollution problem. He believes one reason for Beijing's openness is the lessons learned during the past two months when industrial accidents caused the contamination of two rivers in the country. Authorities were forced to cut the drinking water supply for millions of people for several days.

"It is really high time for the whole country to face the water pollution problem. And no one can deny it actually," added Mr. May. "The problem has developed to an extent that the government has admitted over 90 percent of the water in China has been polluted, so you can't just close your eyes and escape. No way."

Water is a crucial issue for China, which has more than a billion people. The center and northern parts of the country are largely arid, and its deserts are expanding.

As China's economy expands, pressure on water resources will increase. The environmental bureau says the next 25 years will be critical in determining whether the country can stop its water quality from deteriorating further.