It's likely a collapsed section of pipe that stalled Wellington's sewerage system for two days will not be fixed.
The section of pipe, located 20 metres below the ground near Dixon and Willis streets, caved in last week, resulting in thousands of litres of sewage being discharged into the harbour.
The pipe, installed in the 1930s, was already being prepped for repairs after residents had complained of sewage smells when it collapsed.
Wellington Water acting chief executive Jeremy McKibbin said it probably would not be repaired as there were better options.
"It's quite tricky to get to and it will be reasonably difficult to maintain, ongoing. So the route that we've selected is potentially a lot easier ongoing."
McKibbin said details around the permanent fix would be confirmed and work would begin in the new year, but it would likely be a new underground pipe running down Willis St.
Meanwhile, Wellington Water was working to figure out what was caused sewage contamination in the Wellington harbour, despite none being discharged through the overflow pipes for five days.
McKibbin said it would be difficult to locate the source of the leak.
"These things are quite hard to find because they're intermittent. So it could be anything from a DIY plumber connecting their sewer into our stormwater by mistake or a cross-connection of some description. So we're just trying to find out where it's coming from."
He said until that was sorted people should not swim in the stretch of water between the entrance to Whairepo Lagoon, through the dive platform to the Overseas Passenger Terminal.
The rest of the harbour was safe to swim in.