Wang Guixiang has to buy purified water for her family as people in her village do not dare to drink the water from the well anymore, due to serious pollution.

"The well, which was our source of drinking water for years,is just one kilometer away from an industrial park with chemical plants. Water in a river nearby has turned black," complained Wang from Xinzhuangzi Village, in North China's Hebei province.

"Household tap water turns yellow sometimes and we are afraid to drink it," she said. Villagers rely on a single purification device which the village bought two years ago for their drinking water.

Xinzhuangzi was one of the "cancer villages" listed in a thesis paper on the geographical distribution of such villages in China, written in 2009 by Sun Yuefei, a graduate in geography at Central China Normal University in Wuhan city.

The paper claimed the number of such villages should be more than 247 in some 27 provinces or regions on the mainland, but the figures could not be officially confirmed.

"Our three sons all buy purified water to drink as they fear that dirty water may affect their fertility," said another woman surnamed Sun in the same village.

Villages troubled by polluted drinking water and a rise of cancer cases are not rare in China. They are mainly in the developed eastern and coastal regions.

In Hezuitou village, northwestern Shaanxi province, 46 people died of cancer between 1991 and 2003.

"The water in the well tasted sweet before the 1990s, but since the early 1990s, the water had a different smell," said 54-year-old villager Liu Jiqing.

There were paper mills and oil plants near the village. The factories have since closed but untreated domestic sewage and industrial waste continues to pollute a local river and groundwater.

"The years when there was a high rate of cancer were also the period of most serious pollution," said Du Weimin, Communist Party chief of Duying village, in Zhoukou city, Central China's Henan province.

Around ten deaths from cancer were reported each year in Duying village between 2003 and 2010. The village is near the Shaying River, a tributary of the Yellow River, the country's second longest.

A chemical risk control plan issued by the Ministry of Environmental Protection in February this year mentioned serious health and social problems such as cancer villages in some areas.

Quality drinking water is vital to people's health. The rate of cancer cases will be high among people who drink polluted water, according to Li Jinghong, a chemistry professor at Tsinghua University in Beijing.

Drinking water in north China mainly comes from underground and nitrates, ammonia and heavy metals are common pollutants of underground water, said Zheng Chunmiao, a water resource researcher at Peking University.

Some 44 percent of shallow underground water in the North China Plain, which covers Hebei, Henan, Shandong, Beijing and Tianjin, suffer pollution to different degrees, according to a five-year survey completed by the Chinese Academy of Geological Sciences in 2010.

According to figures released by the top environmental watchdog last year, ground water in 57 percent of monitoring sites across China is polluted or extremely polluted. In addition, 298 million rural residents do not have access to safe drinking water.

Government efforts to deal with water pollution are under way.

The Chinese government vowed in March to solve the problems of serious air, water and soil pollution that affect the people's vital interests and improve environmental quality.

China aims to curb the worsening trend of groundwater quality in the North China Plain by 2015 and realize a remarkable improvement of groundwater quality by 2020, according to an official water pollution control plan for the region.

In May, the top environmental watchdog fined 88 companies 6.13 million yuan (about 0.99 million U.S. dollars) for violations resulting in underground water pollution in a 40-day campaign focused in north China.

"Air and water are the most important for people," said villager Sun. "We want the chemical factories nearby to be moved elsewhere as soon as possible."

Sun Bo, head of the Shandong Provincial Department of Environmental Protection, said polluting companies were directly related to the pollution problem facing cancer villages, but government departments should also be held accountable for their approval of such companies.

Polluting companies should be closed and effective measures taken to restore the ecological environment, said Sun.