A new system to measure the quality of water entering the Huangpu River, the biggest source of Shanghai tap water, was installed.

The detection system was needed since tributaries of the Huangpu are from other provinces, said officials of Shanghai Water Environment Monitoring Center.

Adjustments were still being made to the automatic system before operation was to begin.

"The quality of fresh water for tap water treatment is at the mercy of provinces on the upper reaches," said Xu Jiancheng, general engineer with the center.

"Some small factories are discharging polluted waste water into Taihu Lake, the source of Huangpu."

The early detection system with an electronic eye, located at the upper reaches of Huangpu River and three of its tributaries in Songjiang and Qingpu districts, is close to Zhejiang and Jiangsu provinces, where pollution starts.

"The system will collect samples and detect dangerous elements and chemicals," Xu said. "It then analyzes the data. Poor quality water can be reported to authorities earlier than before, and water plants will be informed."

Six substations were installed to collect water samples. A central station nearby receives and processes the information.

More than 6 million yuan (US$722,892) has been invested by the local government and construction started two years ago.

At present about 80 percent of the city's tap water is from Huangpu. The rest is from the Yangtze River. Combined, they supply local water plants with more than 6 million cubic meters daily.

The city is considering reducing reliance on the Huangpu River and taking more water from the Yangtze. It's possible it could happen this year, the Shanghai Water Authority said.

Actually, the deteriorating quality of Huangpu River has been a concern for local water plants.

"We have to make a greater effort to convert fresh water into up-to-standard tap water, and this has increased our cost," said Yu Xiao, Shanghai Waterworks South Co spokesman.

To reduce local pollution, the source of tap water has been moved upstream several times in the past few years.

(China Daily March 8, 2004)