Some 73 percent of water catchments in 30 major Chinese cities is "severely polluted," threatening some 860 million people, a recent report on water quality said.



The China Urban Water Blueprint released on Monday by The Nature Conservancy, a leading nongovernmental organization for global conservation work, indicated that samples taken from 73 percent of watersheds in 30 cities - including Beijing, Shanghai and Guangzhou, Guangdong Province - were either moderately or severely polluted by sediment deposits or nutrients.



The report said that "non-point source" pollution - pollution picked up by rain runoff or snowmelt which then drains into water bodies - caused by improper land use and soil degradation is the primary source of water pollution in most Chinese cities.



"The water security issue is more and more severe in China, and the public health risk related to water supply is due in greater part to water pollution caused by human activities," Zhu Jiang, deputy director-general of the International Economic and Technical Cooperation and Exchange Center under the Ministry of Water Resources (MWR), was quoted as saying by Beijing-based news site yicai.com on Tuesday.



"Damage to ground vegetation causes soil and water loss, which allows mud, sand and even nutrients to flow into the water, leading to pollution," Ma Jun, director of the Institute of Public and Environmental Affairs, told the Global Times on Tuesday, adding that the reclamation of land from lakes, excessive land reclamation from other ecosystems and overuse of chemical fertilizers and pesticides will also impact water quality.



According to the report, over 69 percent of water supplies for all of China are now provided by catchment areas occupying only 6 percent of the country's total land area.



"With the aggravation of water quality and the decline of the water table, many regions in China are having to give up many sources of water, so the area of water catchments has been contracting in past years," Ma said.



The Nature Conservancy argued in its report that non-point source pollution should be addressed by protecting water catchment areas and by improving methods of managing and using land within water catchment areas.



Meanwhile, a monthly MWR report published on April 11 stated that over 80 percent of underground water from 2,103 monitored wells throughout China is unfit for human consumption.