Real-time information about the quality of water available from the country's major rivers will now be available online.

The Ministry of Environmental Protection (MEP) began publishing results of tests on surface water quality at 100 locations yesterday. The information is updated every four hours.

The quality of surface water is not directly linked to tap water, but monitoring rivers and lakes can help ensure the safety of the water supply, especially when contamination accident happens, MEP officials said.

Ma Jun, director of the Institute of Public and Environmental Affairs, said publishing real-time monitoring results is "a step forward" for environmental information disclosure in China.

"Publishing air and water quality will help ensure and protect the public's access to environment-related information," said Ma. But he added that the information should be more "user-friendly", for example, how the data is affecting the public.

Five indicators, such as pH level, dissolved oxygen (DO), total organic carbon (TOC), chemical oxygen demand (COD) and ammonia nitrogen, are being used to gauge the water quality of China's seven major rivers and three lakes, as well as tributaries in the southeast and southwest.

Previously, China published COD as a major index for water pollution. Providing additional data will help to give the public a thorough picture of water quality in major rivers, according to MEP. For instance, DO and TOC determine the degree of organic contamination, while ammonia nitrogen, a major chemical compound that boosts the growth of blue-green algae, reflects the industrial and agricultural pollution in a certain area.

In China, tap water is supplied by drinking water sources and filtered at water plants.

During the summer of 2008, monitoring pH level and DO at Taihu Lake in Jiangsu province helped predict the outbreak of blue algae and avoided a crisis similar to the one in Wuxi in 2007, MEP said. In May 2007, the water supply was cut off at the lake-side city, with a population of more than 5 million, after Taihu Lake started to stink with a blue-green algae bloom. Citizens complained that tap water was so tainted and smelly they could not wash with it or drink it.

(China Daily July 2, 2009)