Environmental protection departments nationwide were ordered on Thursday to make all-out efforts to tackle companies and projects that threaten the safety of China's drinking water sources.

Zhai Qing, the vice-minister of ecology and environment, called on local authorities to take urgent action to root out those who violate laws and regulations designed to prevent pollution.

"If we fail to ensure safe drinking water for the public, we will let the central authorities down," Zhai said as he presided over a video conference.

Inspections this year of 1,586 lakes and waterways that supply drinking water uncovered 6,251 environmental violations. These water bodies supply every city in the Yangtze River Economic Belt and many more nationwide.

About 95 percent of the violations have been addressed, Zhai said, with 12 provincial regions including Shandong, Sichuan and Fujian given a 100 percent pass. Another 17 have cleared 90 percent, he said.

However, Zhai added that the remaining violations would be "hard nuts to crack". These include 149 violations related to agricultural pollution and 39 related to industrial emissions, as well as 16 illegal sewage drains in protected areas that supply drinking water.

The State Council published an action plan focused on environmental protection in areas around drinking water sources in March. It vowed to root out violations discovered by inspectors by the end of this year.