Christchurch City Council is developing a new strategy for increasing the health of the city's rivers, wetlands and harbour.
The Three Waters Strategy, which will also fix and adapt infrastructure, will be developed over the next 12 months.
Council spokesperson Helen Beaumont said since the earthquakes both the council and residents were more conscious of the state of the city's water and everything that affected it.
The council said it could take 30 years before its sewerage system was returned to a pre-earthquake condition.
A council report said there was a risk the money set aside to fix the pipes would not be enough, and increased amounts of raw sewage might have to be released into the city's rivers for years to come.
The money set aside has been provided by both central and local government.
Council manager in charge of sewage Tim Joyce said that meant the council was having to cut its cloth to measure.
He said the plan was to get the most out of the existing system, and over the next 30 years bring things back to where they were before the quakes.
Mr Joyce said a definitive answer on the scale of the repair job, which the government was leaving the council to deal with, would not be known until 2017, but he admitted early indications were not good.