"We cannot conclude that water sources are good quality just because routine indicators meet the criteria."

Ling Jiang, deputy director of the pollution prevention department at the Ministry of Environmental Protection, said at an ecological forum in Guiyang that ended on Sunday. Although 95.3 percent of monitored drinking water sources in 113 major cities met national standards last year, people should not be unconcerned, Ling said, adding China has no special national standards to monitor drinking water sources.