A wastewater pipe has burst at the intersection of Victoria Street and Mercer Street in central Wellington.
The city’s water manager, Wellington Water, said waste water was leaking onto the road.
It said there were no signs so far that water had seeped into Wellington Harbour or Whairepo Lagoon.
Greater Regional Council and Regional Public Health have been notified.
Wellington Water said crews and contractors were trying to repair the pipe and trucks were also on site to minimise any discharge to the harbour.