Water flowing through Hong Kong and Macao special administrative regions is safe to drink despite the increasing number of environmental incidents on the Pearl River in recent years, the river's monitor agency said.

There has been a string of environmental scandals across the country in recent years in the wake of the construction boom of chemical plants alongside rivers.

"So far, pollutants in the Pearl River can be diluted and absorbed within certain river sections, which pose no substantial impact on the whole river," Liu Zhisen, an official on water resources protection from the Pearl River Water Resources Commission, told China Daily.

"The quality of river water sources to Hong Kong and Macao is up to grade II, a higher standard for drinking water," he said.

The Pearl River, China's third-longest river, is a major water supplier to Hong Kong and Macao.

Since the 1990s, Dongjiang River, a trunk stream of the Pearl River, has satisfied 70 to 80 percent of Hong Kong's fresh water demand.

In a recent case in January, cadmium pollution in the upper Longjiang River posed a potential threat to the water supply in the downstream city of Liuzhou, which has 3.7 million residents.

Cadmium is a highly toxic heavy metal used in batteries, electroplating and industrial paints. Exposure can lead to liver and kidney damage, and result in death.

Since the Longjiang River flows into the Pearl River, people in Hong Kong and Macao were worried about the safety of their water supply.

"A 24-hour monitor system on water quality has been launched along the river, focusing on illegal discharge of waste and other pollutants. Therefore, any pollution can be timely discovered and controlled as soon as possible," Liu said.

Last year, authorities handled 542 environmental incidents across the country, according to statistics from the Ministry of Environmental Protection.

Nearly 60 percent of the incidents were triggered by traffic accidents and work safety accidents, Ling Jiang, deputy director of the department of pollution prevention and control under the ministry, told China Daily.

Contact the reporter at jinzhu@chinadaily.com.cn