Over half of China's 668 cities are facing severe shortages of adequate underground water.

Illnesses related to unhygienic water still exist in many areas, leaving over 70 million people using sub-standard underground water, according to a recent report from the Ministry of Land and Resources.

The report is based on the country's second national survey on underground water resources which was started in year 2001 and wrapped up earlier this year.

It's time for local governments to impose stricter measures to improve the situation, said Jiang Jianjun, director of the Geological Environment Department under the ministry.

Jiang said excessive exploitation of underground water is to blame for most of the troubles.

According to him, the country's extraction of underground water has increased by an average annual rate of 2.5 billion cubic meters over the past two decades and reached a total of 119.1 billion cubic meters last year.

Underground water now comprises 30 per cent of the country's total urban water supply, but due to environmental problems caused by excessive extraction, only 63 per cent of China's urban areas enjoy underground water that is potable without treatment.

One explanation of this is that the same amount of pollutants now has less water to dilute, said Xu Huizhen, an expert with the China Institute for Geo-Environment Monitoring.

But the negative impact goes beyond deteriorating underground water quality. Land subsidence and the invasion of seawater are other major concerns.

"Most of these negative impacts were not very noticeable initially, but now they are too huge to be ignored,'' said Xu.

For example, due to ground subsidence, some bridges over the Yangtze River in East China can no longer accommodate ships passing under them. And East China's Zhejiang Province had to adopt a local regulation to limit the extraction of underground water last year. Otherwise, severe ground subsidence might have drastically increased tidal plains in some of the province's seaside cities by 2030.

"But before that (year 2030), the invasion of sea water to take up the place originally occupied by fresh underground water might have already given local people a hard time,'' said Yu.

"Serious invasion of sea water might leave those cities little good fresh underground water to use.''

Although more and more regions are using such measures as increased prices to promote water conservation, Zhang Zonghu, an academician of both the Chinese Academy of Sciences and the Chinese Academy of Engineering who led the latest national survey on underground water resources, highlighted the importance of water use efficiency.

"To produce industrial products of the same value, the water we consume is 10 to 20 times that used by the advanced countries. As for 1 kilogram of grain, we need one to two times more water as well,'' he said.

(China Daily November 3, 2003)