An RNZ reporter said the right-hand lane on the one-way route was closed, after the force of the water buckled the road and cracked the pavement.
NZ Transport Agency said due to flooding, the right-most lane between Taranaki Street and Tory Street was blocked.
The road was the southern part of State Highway One to the airport and eastern suburbs.
Motorists were warned to expect delays on Thursday afternoon as traffic on the major thoroughfare had to form a single file.
Wellington Water said in a statement it had responded to a burst main on Vivian Street, in the suburb of Te Aro.
Just before 3pm it said it was assessing the shutdown area and water would soon be turned off.
"It is anticipated that service will be interrupted for at least five hours."
An hour later, it said a team had successfully isolated the drinking water pipe and they were progressing with the repairs.
A man working nearby alluded to the city's cycle lanes controversy, saying he thought the council was putting in a kayak lane, and lamented the impact on local businesses.
Another person working on a nearby building said water had been cut off for about half an hour, and most of his work mates sent home for the rest of the day.
Council contractors working with jackhammers had drained much of the flooding by 4pm.
