pollution.""Without water，"agrees Pan Jiahua, of the Chinese Academy of Social Sciences, "people cannot survive in a desert." Wang Shucheng，a former water minister, once said, "To fight for every drop of water or die. That is the challenge facing China." He was not exaggerating (夸大).

China uses 600 billion cubic meters of water a year. The national average hides an even more alarming regional difference. Four fifths of China's water is in the south, particularly the Yangtze River basin. Half the people and two thirds of the farmland are in the north, including the Yellow River basin. Beijing has the sort of water shortage usually associated with Saudi Arabia: just 100 cubic meters per person a year.

China is using up water at an unsustainable (无法可持续的) rate. As if that were not bad enough, China is polluting what little water it has left. The Yellow River is often called the cradle of Chinese civilization. However, a third of the water is unfit even for agriculture. Four thousand petrochemical factories are built on its banks.

　　The water available for use is thus so bad. Song Lanhe, chief engineer for urban water quality monitoring at the housing ministry, says only half the water sources in cities are safe to drink. More than half the groundwater in the North China Plain cannot be used for industry, while seven tenths is unfit for human contact, even for washing.

　　The best answer would be to improve the efficiency (效率) with which water is used. Only about 40% of water used in industry is recycled，half as much as in Europe. The rest is dumped in rivers and lakes. Wang Zhansheng of Tsinghua University argues that China is neglecting its urban water infrastructure (基础设施), leading to more waste. Water prices in most cities are only about a tenth of the level in big European cities, yet the government is unwilling to raise them, for fear of a popular criticism. The result is that Chinas "water productivity" is low.

Rather than making wise reforms in pricing and water protection, China is focusing on increasing supplies. The best known such projects are the Three Gorges