The Christchurch sewerage system suffered six times as much damage in the February earthquake as it did in the September earthquake.
Media were taken on a tour of the damaged treatment plant in Bromley on Wednesday.
All four of the plant's clarifiers have stopped working, which means more solids are in the waste water being pumped into oxidation ponds.
Work is underway, including sending divers into the ponds, to get them operating again.
A huge quantity of silt is also making its way into the plant with the sewage. In the last month alone, twice the amount of silt that would normally get into the plant in a year entered the system.
Christchurch City Council water and waste manager Mark Christison says to limit the amount of silt getting in, people need to reduce the use of their toilets.
The removal of silt from pipes is expected to continue for at least three or four months, he says.