HARBIN, China (AP) -- Authorities were making last-minute preparations Sunday to restore running water to 3.8 million people in this northeastern Chinese city who were spending a fifth day without supplies after a toxic spill in a nearby river.Water service was due to resume at 11 p.m. (1500 GMT) after visiting Premier Wen Jiabao told local leaders on Saturday to see that every resident got running water.Work crews were installing more than 1,000 tonnes of carbon filters at water plants in preparation for treating water from the Songhua River once it is deemed safe, according to state-run media."We cannot allow even a single person not to have water," Wen said at a meeting of local leaders Saturday, according to state television.Wen promised a full investigation of the November 13 explosion at a chemical plant in a neighboring province that spewed 100 tonnes of toxic benzene into the Songhua. State media have criticized local officials for reacting too slowly and failing to tell the public the truth about the disaster until this week.Pictures of Wen visiting a water plant and the home of a Harbin family were on the front pages of local newspapers Sunday in an apparent effort to reassure the public about Beijing's concern for their safety.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."Li Zhaoxing expressed his sincere apology on behalf of the Chinese government for the possible harm that this major environmental pollution incident could bring to the Russian people downstream," state television said on its national evening news.Beijing is eager to repair its damaged standing with both its public and Moscow, a key diplomatic partner.The government said benzene levels in the Songhua near Harbin had dropped below the official safety limit on Saturday. But it said a second toxin, nitrobenzene, was still above acceptable levels.The announcement this week that Harbin would shut down its water supply set off panic-buying of bottled water.On Sunday, residents lined up for another day in freezing wind holding out buckets and teakettles for water provided free of charge and delivered by truck from wells operated by factories and a beer brewery.The explosion at the chemical plant in Jilin, a city about 200 kilometers (120 miles) southeast of Harbin killed 5 people and forced the evacuation of 10,000.But a full week went by before the government announced that the river had been poisoned with benzene.The spill has been an embarrassment to President Hu Jintao's government, which has made a priority of repairing environmental damage from 25 years of sizzling economic growth, and of looking after ordinary Chinese.Chinese officials say the toxins should reach Russia in about two weeks. Officials in the border Russian city of Khabarovsk were preparing an emergency plan including the possible shutdown of the city's water system.Oleg Mitvol, deputy chief of Russia's Federal Service for Supervision of Natural Resources, visited the Khabarovsk region Saturday. In remarks broadcast by Russian television, Mitvol said he had arranged for a quick upgrade of the city's water purification facilities.Earlier Saturday, Wen visited the Harbin No. 3 Water Filtration Plant, where 300 paramilitary police were delivering some of the 1,400 tonnes of activated carbon sent to the city for water filtration once the Songhua is deemed safe to use.Copyright 2005 The Associated Press. All rights reserved.This material may not be published, broadcast, rewritten, or redistributed.