Wellington's water provider expects it will take several days to repair a broken wastewater pipe at Eastbourne.
Wellington Water said the problem at the Days Bay pump station happened on Saturday afternoon.
Crews were stood down overnight because of the incoming high tide and poor light.
As part of preparations for repair work, the main wastewater outfall pipeline to Pencarrow Heads has been temporarily closed off.
As a result, fully treated wastewater is being discharged into the Waiwhetu Stream.
This was being done to manage flows to ensure the safety of crews before work began to repair the pipe.
Wellington Water spokesman Jeremy McKibbin said everything possible was being done to minimise the environmental impact.
It was a complex repair in a coastal environment with multiple wastewater pump stations in the immediate area, he said.
Eastbourne residents are being asked to reduce the use of toilets and showers, to ease pressure on the wastewater network.