A surge of toxic chemicals pouring down the river through a northeastern Chinese city is expected to have passed through by early tomorrow morning.
As the nine million people in Harbin suffered a fourth day without running water, soldiers and workers raced to ensure the city's water would be safe to drink when taps were turned back on, installing new filters at treatment plants, state media said.
The pipe network was shut down on Tuesday evening to protect Harbin residents from up to 100 tonnes of cancer-causing benzene compounds spilt into the Songhua river from which Harbin pumps its water. An explosion at a chemical plant upstream triggered the release of the toxins.
The spill could affect hundreds of thousands more people in China alone as it heads downstream, and then crosses into Russia, although officials say the concentration of toxins will fall as other tributaries join the river, the China Daily reported.
Benzene levels in Harbin were down to 2.3 times officially acceptable levels on Saturday compared to 30 times on Friday morning, the city government Web site said.
But the passage of the 80 km slick, flowing at around 2 km an hour, has been slowed by low water levels and lumps of ice that have already formed on the freezing water. Late on Friday, teams used picks and crowbars to break up the ice.
Harbin city officials told local newspapers they have prepared a plan to restore tap water to residents but urged caution.