Niu Siwei's sense of unease grows each time he hears his students cough.

After eight months with no rain, the village school where he teaches in Nanhua County of Chuxiong, a Yi ethnic prefecture in southwestern Yunnan Province, has been using water from a local fish pond for cooking.

A child is lining up for drinking water in Xiaoyangchang Village, Fuyuan County of Yunnan Province, on March 12, 2010. Parts of southern China are being ravaged by a severe three-season drought. More than 20 million of people lack adequate water supplies, and millions of acres of cropland are too dry to plant.

The feculent water is sterilized with bleach powder, so the meals for the 192 students, aged 7 to 12, always have a strong smell of the chemical.

"At the beginning, the cook believed the more bleach powder he used, the safer the water would be," said Niu. "Once he put 10 grams in 100 kg of water, almost 10 times the safe amount."

Last week, some thirsty students took a few mouthfuls of unprocessed pond water, and became sick vomiting and had diarrhea.

The once-in-a-century drought that has left almost 20 million people thirsty in China's southwestern localities, including Yunnan, Guizhou, Guangxi, Sichuan and Chongqing, has aroused widespread concern.

As a result, donations of drinking water are arriving.

Nongfu Spring Co., a bottled water producer in the eastern province of Zhejiang, was the latest donator. It decided Monday to send 13 million yuan (1.9 million U.S. dollars) worth of bottled water to the drought-hit province.

The donated water, however, averages only 600 ml a day for each student, less than half of the daily per capita requirement.

Three times a week, Niu takes his students to fetch water from a pond 1,000 meters from school. "Even the girls carry about their own weight in water, and a two-way trip takes only 15 minutes."

But the pond, too, has little water left.

Chuxiong, one of the poorest areas in China, is not alone.

In Qujing City, many villagers have to wait 48 hours before they can fetch a bucket of water at the few sources still in service.

Every day, 5-year-old Liao Mingbo joins the queue, carrying 2.5 kg each time. "It's not heavy. I've been doing this for many months."

Liao's fellow villagers in Huize County must walk about two and a half hours to get to a river for water.

"For generations, we relied on rain for drinking water," said villager Wang Zhengyi. "But our water cellars dried up months ago. We're busy carrying river water every day to survive. Who cares about the crops?"

The drought has damaged at least 3 million hectares of cropland in Yunnan Province, according to figures released by the national flood prevention and drought relief headquarters in Beijing. Many peasants complain all their wheat, beans and vegetables have died.

The drought has cut the province's power generation capacity by 30 percent, as it largely relies on hydropower, and water flow in the Lancang River, Asia's third longest, was down by half compared with last year.

If the drought continues, almost a quarter of the local population will suffer drinking water shortages by May, said Zhou Yunlong, chief of water resources in Yunnan.

The province has a population of 45.5 million, according to the most recent census in 2008.

WIDER GRIM PICTURE

Yao ethnic minority residents in the mountainous Nengwai village in Guangxi have to walk more than one hour to fetch water on horseback from a river seven kilometers away.

In Guangxi, the drought has damaged 476,050 hectares of crops and left 2.2 million people with drinking water shortages.

Many reservoirs have dried up, with huge cracks appearing on the reservoir bottoms. The dry weather has forced the closure of more than half of hydropower stations in Hechi City.

In Sichuan, the drought is worsened by higher than normal temperature since mid March. The temperature in Sichuan Basin is seven to 10 degrees Celsius higher than average levels.

In Panzhihua City in Sichuan, there has been no rainfall for almost half a year and so it is even a luxury to take a bath or wash dishes. Some villagers even haven't taken a bath for two months.

In mountainous Guizhou, more than 3 million residents are short of food.

The once famous and powerful Huangguoshu waterfall has now become more like a stream. The waterfall is at least the smallest size since it was opened to public in 1980s, said Wang Daoxiang, deputy general manager of Huangguoshu Tourism Group Co..

In Anshun City where the waterfall is located, more than 90 percent of rivers and reservoirs have dried up.

The drought, already the worst in sixty years, will continue to worsen as Guizhou expects no substantial rainfall in the coming month, according to local weather forecasts.

NATIONAL CONCERN

The severe drought in the southwest have grabbed media headlines and become increasingly a major national concern. It has left tens of millions residents with water shortages and caused direct economic losses of 19 billion yuan (2.8 billion U.S. dollars).

Premier Wen Jiabao paid a three-day trip to Yunnan that ended Sunday to direct relief efforts.

Wen said priority should be given to drinking water supply and preparations for spring farming, urging local authorities to prepare for the worst as the drought "is likely to continue".

The world marked the 18th water day on Monday, as lack of water has become a global issue, with the United Nations estimating that by 2025, two-thirds of the planet's population will live with water shortages.

China in particular faces severe shortages in its goal for more sustainable economic and social development. Its per capita freshwater resources were only 2,200 cubic meters, about a quarter of the world average.

Of China's 600 cities, more than 400 suffer chronic water shortages, according to Ministry of Water Resources.

Chen Lei, Minister of Water Resources, told Xinhua that China will step up water conservation and environment protection and put in place strict management on water resources to tackle the increasingly acute water shortages.

Chen added that China has a huge population but small water resources that were unequally distributed among geographical regions and four seasons.

For the northwestern province of Gansu, drought is routine. In its Huining County, residents are storing up water for possible water supply cut-offs.

The county was hit by widespread tap water supply disruption from late April to early May last year.

"We used to see drought in nine of ten years, but now there is likely a drought each year," said Zhang Xu, government head of Liujiazhai township in Huining. The county received 120 mm of rainfall in 2008 and 90 mm in 2009.

"We won't be able to plant spring crops should there be no rain," said Chen Peng, a villager in Liujiazhai.