Priority sectors include households, enterprises, heating service departments, government departments, colleges and universities, hospitals, hotels, restaurants, primary and middle schools, and kindergartens.
Car washes and bathhouses have been required to suspend services temporarily.
In addition, the city will introduce a three-level water quality warning forecast system.
"Red" means the water is not suitable for drinking or using, "Yellow" means the water is suitable for using but not for drinking, and "Green" means that the water meets drinking quality standards.
Results will be published and broadcast in the local media.
Harbin, capital of Heilongjiang Province and home to 3.8 million people, was forced to shut down its water supplies system on Wednesday because of contamination of the Songhua River, the city's main water source.
Toxic benzene and nitrobenzene flew into the Songhua River following a chemical plant blast at the China National Petroleum Corporation (CNPC) Jilin Petrochemical Company in neighboring Jilin Province on November 13.
Benzene is a clear, colorless, highly refractive flammable liquid that is derived from petroleum and used in or to manufacture a wide variety of chemical products, including detergents, insecticides and motor fuels.
China is able to tackle pollution emergencies
"It is an unprecedented incident for a city with millions of people in China to face such severe water pollution, which makes decision-making and treatment even more sensitive," Zhang Zuoji, said.
The provincial government has allocated 10 million yuan (US$1.23 million) to tackle the emergency and has launched 24-hour monitoring of water quality.
In addition, the city of Harbin started a coordinative emergency response mechanism that grouped relevant governmental departments together, such as water supply, heating supply, medical care and public security.
"I was very worried when I first heard that water would be stopped, but later when I saw a great many cars carrying pure and bottled water in the streets and the water at supermarkets were sold at normal price, I felt much relieved," said Sun Xiuyun from Nangang District.
To ensure water supply for heating service and hospitals, 945 new deep groundwater wells were dug.
Shi Wenqing, vice mayor of Harbin, said his city government had set aside one million yuan (about US$125,000) to provide drinking water for free to the needy.
Telephone, TV, radio, Internet and text messaging hotlines were also set up to offer psychological help and to answer general questions on water supply.
With the coordination of the central government, a total of 1,000 tons of activated carbon from other provinces and regions like Hebei, Ningxia and Shanxi were shipped to Harbin by Sunday to help purify the river water.
In a meeting with Russian ambassador Sergei Razov in Beijing on Saturday, Chinese Foreign Minister Li Zhaoxing informed Russia about the water pollution and apologized to Russia over the possible consequences on the lives of the Russian people when the toxic slick flows into Russia.
In Nairobi, Zhang Shigang, China's deputy permanent representative to the United Nations Environment Program (UNEP), met with the UN agency's Deputy Executive Director Shafqat Kakakhel on Saturday afternoon and gave him a thorough briefing on the disaster, pledging to provide updates on the incident to the international community on a daily basis.
According to the city government, no case of benzene poisoning has been reported.
(Xinhua News Agency November 28, 2005)
