Christchurch City Council is asking people go easy on essential services or risk their collapse.

Residents are urged to continue using portable toilets as the council works to avoid odour problems from untreated sewage.
Silt from February's earthquake has collected in the main sewers and waste water is flushing it into the sewage treatment plant at Bromley.
Water and waste manager Mark Christison says the silt is clogging the plant and forcing engineers to pump untreated sewage into oxidation ponds.
He says overloading there would mean the smell of raw sewage could linger in Christchurch for months.
Mr Christison says silt is being removed from the sewers and the pumping station, but it could be four to six months before all the silt is cleared from the network.
And police urge drivers to slow down. They say driving around the city remains hazardous, but motorists are ingoring speed restrictions on unstable roads and bridges.
Superintendent Andy McGregor says drivers must slow down around schools and road works in particular.
Meanwhile, heavy trucks carrying demolition rubble to the Burwood landfill are now using a new route that avoids densely populated residential areas.
b Winter power supplies
Residents in the eastern suburbs are worried that the damaged electricity grid will struggle to supply enough power for household heating appliances this winter.
Orion says it's possible that more underground power lines will fail in winter as electricity loads increase.
But chief executive Roger Sutton says the lines company is bringing in more diesel generators as a back-up measure and is building new overhead power lines.