Environmental protection officials yesterday urged local governments to ward off heavy- metal pollution and beef up efforts to ensure the safety of drinking water.

The quality of one-fifth of the country's drinking water sources failed to reach national standards, leaving 90 million people with no access to clean water, Zhang Lijun, vice-minister of environmental protection, told the first national conference on drinking water protection held in Shenyang yesterday.

In urban areas, tap water is supplied by 4,000 centralized drinking water sources, including rivers, lakes, reservoirs and underground reserves.

"The result is based on routine monitoring, which examines only basic pollutants. At these source areas, the concentration of some pollutants, such as coliform bacteria and ammonia nitrogen, is higher than the national standards," Zhang said.

"If we use the 109-indicator evaluation system, which includes tests on the concentration of heavy metals and organic toxins, the result will be worse," he said.

China has been faced with an increasing number of major heavy-metal pollution incidents. Several lead poisoning cases involving thousands of children across the country have sparked protests earlier this year.

Some local governments are still putting more emphasis on economic growth than on the environment and people's health, Zhang said. He urged officials from local environmental protection bureaus to stick to their responsibilities and not approve projects that pollute.

"I've learned that in some areas, local governments are trying to shrink the protection zone for drinking water sources, to make room for more development projects, regardless of their impact on the environment," Zhang said.

Protection zones have been designated for each drinking water source, where industrial projects are forbidden in order to ensure no sewage is discharged into the water source, according to the regulations formulated by the Ministry of Environmental Protection.

"The ministry and local protection bureaus should never approve a request for re-designing the protection zone for such purposes," he said.

Zhang also told local environment authorities to be wary of industrial projects that involve heavy metals, such as lead, mercury, cadmium, chromium and arsenic.

The ministry is revising a plan for heavy-metal pollution. The State Council will release the plan soon, Zhang said.

The protection of drinking water is also hampered by insufficient water quality monitoring equipment. Most of the country's environment monitoring stations still do not have the facilities to carry out examinations for all the 109 water pollution indicators.