Running water was restored Sunday in this city of 3.8 million people where a chemical spill forced a five-day shutdown, but officials warned it was not immediately safe to drink.

Water supplies resumed in Harbin at 6 p.m. — about five hours earlier than expected, the official Xinhua News Agency said. It said tests showed a 50-mile spill of toxic benzene in the Songhua River had passed the city in northeastern China.

State television showed the governor of Heilongjiang province, where Harbin is located, drinking a glass of boiled water drawn from a tap at a local family's home.

"It tastes good," said Gov. Zhang Zuoji.

But Wang Minghe, deputy general manager of the Harbin water department, said the water was still "dangerous" to drink "because it's been sitting in pipes for five days." He said it should be used only for other purposes, such as washing.

"We will advise citizens when they can drink the water," he told reporters on a tour of a water-treatment plant.

Wang did not say how soon the water might be considered safe for drinking.

The government will cut water fees to encourage the public to use water as quickly as possible over the next few days to flush out the old supply and "enable it to be drinkable sooner," Wang said.

Earlier Sunday, Liu Yurun, general manager for the Harbin Water Group, the city's water utility, said local radio and television stations would broadcast a color-based indicator of water safety over the next few days — red for unusable, yellow for bathing only and green for drinking.

Work crews were installing more than 1,000 tons of carbon filters at water plants in preparation for treating supplies from the Songhua, according to state media.

Before service resumed, people lined up for another day in freezing wind holding out buckets and teakettles for free water delivered by truck from wells operated by factories and a beer brewery. The city also had trucked in millions of bottles of drinking water and said it was drilling 100 new water wells.

The Harbin disaster resulted from a Nov. 13 explosion at a chemical plant in Jilin, a city about 120 miles southeast. Five people were killed and 10,000 evacuated.

But it was only last week that the government announced the Songhua had been poisoned with 100 tons of benzene. The spill is possibly the biggest ever of the chemical, a potentially cancer-causing compound used in making detergents and plastics.

State media have criticized local officials for reacting too slowly and failing to tell the public the truth promptly. Environmentalists have said the government failed to prepare for such a disaster and questioned the decision to allow construction of a plant handling such dangerous materials near important water supplies.

Premier Wen Jiabao promised a full investigation when he visited Harbin on Saturday and told leaders to see that every resident got running water.

Pictures of Wen visiting a water treatment plant and Harbin residents were on the front pages of newspapers in an apparent effort to assure the public of Beijing's concern for their safety.

The spill is an embarrassment to President Hu Jintao's government, which has made a priority of looking after ordinary Chinese and of repairing environmental damage from 25 years of sizzling economic growth.

Also Saturday, the Chinese foreign minister made an unusual public apology to Moscow's ambassador to Beijing for damage caused by the benzene spill, which is flowing toward a city in the Russian Far East.

Officials in Khabarovsk were preparing emergency plans, including the possible shutdown of its water system. A senior Russian official visited the city Saturday and said its water purification system was being quickly upgraded.

Meanwhile, authorities in southwest China, where another chemical plant accident sparked fears of a second chemical leak, said contamination of a nearby river was under control, Xinhua reported Sunday on its Web site.

State media said the blast that killed one worker occurred Thursday in Dianjiang, a county in the Chongqing region. Schools were closed and about 6,000 people were evacuated.

More than 800 residents and Communist Party members were helping clean the contaminated portion of the Guixi River using screens made of straw and charcoal, Xinhua said Sunday. Water samples were being tested every four hours, it said.

The report did not say what kind of chemicals had tainted the river but said water supplies were safe.

Also Sunday, Sina.com, a popular Chinese news Web site, reported that the central city of Lengshuijiang had its water supply suspended for 12 hours last week after waste water containing ammonium nitrate was discharged into a nearby river.

The spill occurred when a wall holding back the waste collapsed, but tests showed the pollution did not rise to unacceptable levels and would not affect cities downstream, the site said.