Antibiotics have been found in China's surface water, even in the tap water supplying millions of people in cities, a new investigation found.

Conducted by China Central Television in October and November, the investigation found surface water in major Chinese rivers such as the Yangtze River and Pearl River contain various antibiotics, which have also been found in tap water samples in Nanjing, Jiangsu province.

The concentrations of these antibiotics are far below the levels of medical doses, said Zhang Yunhui, a water professor at the School of Public Health at Fudan University, adding that antibiotics are not listed in national safety standards for drinking water.