"At this stage we can't confirm whether or not this break is to do with the previous repair.
"The water has been shut off, but no customers are without water."
Auckland Transport has warned traffic will be diverted all day and people should allow extra time to travel. Bus services are also affected.
The 200m stretch of road approaches Britomart and is heavily used by buses. Auckland Transport said bus stops on Queen St between Victoria St and Customs St were affected.
The City Link, the Inner Link, the 105 and 106 services have all been diverted. Details are available by calling 09 366 6400, AT tweeted, adding: "We apologise for the inconvenience."
The footpath remains open.
The burst main comes after drought-stricken Auckland had its first good helping of rain in weeks, with downtown Auckland recording 12.55mm of rain in 24 hours.
