Electricity lines company Orion says it has now restored power to 95% of its customers after Saturday's magnitude 7.1 earthquake.
However, chief executive Roger Sutton says it may be two to three days before some customers get power and in extreme cases it may be up to five days.
He says electricity will not be fully restored until the point of supply to badly damaged buildings is isolated, to avoid fire risk.
Up to 30% of residents without running water
Between 15% - 30% of Christchurch residents were without running water on Sunday and some streets may not have a supply for several days.
The worst affected areas are the eastern suburbs and Halswell. Eight pumping stations have been severely damaged.
Council controller Kevin Locke said the broken mains were being assessed from first light on Sunday, but urged people to conserve water if possible.
He said there is a tanker of fresh drinking water at Linwood High School for those without.
The council was shutting down broken mains so pressure in the system could increase.
Gas supply not affected - Contact
Contact Energy advises people to check that gas pipes are properly connected to their home and that gas bottles are standing upright.
Managing director David Baldwin says the gas supply was not affected by the earthquake and is safe to use.
He says crews have inspected all the main lines for leaks and the infrastructure supporting the city's gas supply is in working order.
Mr Baldwin says people should phone Contact Energy's customer service line if they can smell gas.
