The break is impacting supply to Peacock Lane, PeacockRow, Redemption Row, Saint Vincent's Road and the surrounding areas.
Crews are working to repair the main as soon as possible- the estimated return of water supply is 3pm.
Irish Water say it may take 2 or 3 hours after that time for supply to fully return to homes and businesses.
Meanwhile the repair of the road is likely to take a number of days.
The utility says they understand the inconvenience and have thanked customers for their patience.
