Water has been restored to the pockets of Christchurch which were cut off following Saturday night's big 5.3 magnitude aftershock.
The quake caused 12 pipes to burst in the Lyttelton, Redcliffs and Mt Pleasant areas.
But Civil Defence says while the water is back on it will take some time to assess if there is any more damage to the sewerage system.
Civil Defence says the Christchurch City Council will organise a collection of silt brought to the surface by the aftershock.
The earthquake created another round of liquefaction in some parts of the eastern suburbs.
National Civil Defence Controller John Hamilton says it is not nearly as severe as the big quake in February but there is more sand and silt and some minor flooding.
He says council is asking people, if they can, to clear the silt from their property and leave it on the side of the road, but not near drains because of stormwater.
Drivers must still take care
Mr Hamilton says drivers need to be careful on the roads, because of the heavy rain, and the pockets of liquefaction caused by the aftershock.
He says people should observe the 30 kilometre an hour speed limit in affected areas.
Mr Hamilton says until engineers complete their assessment in Christchurch's central city, no access will be granted for business owners into the red zone.
Engineers have been in the city centre on Sunday to assess any further damage and will report back on Monday morning.
The demolition of the Strategy Building in Victoria Street is underway after it began leaning following the aftershock and nearby roads are closed.