Shanghai will source up to 60 per cent of its tap water from the Yangtze River in a bid to improve its water quality up to the level available in developed countries by 2020, said a local water authority.

The city currently relies on the river for about 30 per cent of its tap water.

Changing water sources, renovating transmission pipes and building new waterworks are among the measures the city is taking to improve the quality of its tap water, said Zhu Shiqing, deputy director of Shanghai's Water Affairs Bureau.

Zhu said the larger share of source water from the Yangtze River would offset the declining share from the heavily polluted Huangpu River, which is now the main source of the city's drinking water.

"The Huangpu River accounts for about 70 per cent of the city's water supply, but its water quality is worse than that of the Yangtze," said Zhu.

The local government is building several big reservoirs at an estuary of the Yangtze River, Zhu said.

The Qingcaosha Reservoir, which lies west of Changxing Island at the mouth of the Yangtze River, will provide 7.2 million cubic metres of fresh water per day after it is finished in 2010. The project is expected to cost the local government 16 billion yuan (US$2.05 billion).

The Shanghai water authority would like water from the Yangtze to eventually account for 60 per cent of the city's water supply. It currently accounts for about 30 per cent, said Chen Guoguang, vice-director of the Shanghai Water Supply and Water Quality Monitoring Centre.

Chen said work is also underway to adjust the city's water supply system. By 2010, four major waterworks in the city centre and a further eight in the suburbs will take over the work of the city's 160 existing small waterworks, which will be closed.

The low quality of the city's drinking water is the source of constant complaints by Shanghai residents. The biggest complaint is the strong chlorine taste of the city's water.

Chen said the water authority put chlorine into the processed tap water to kill germs and bacteria.

"The chlorine might have spoiled the taste, but we must do that to ensure the quality," he said. "And the quality of Shanghai's tap water meets national health standards and is safe to drink."