The leak caused residents and businesses in the Newport section of the city to have reduced water pressure.
Newport, which includes about 16 high-rises, could have reduced water pressure for 24 hours.
Water tankers will be brought into the area as a precaution.
An estimated 2,000 customers are being affected by the leak.
United Water Company says a construction crew is on site to pinpoint the location of the leak, which occurred underground.
Water pressure in the Newport area is expected to be low during repairs.
Customers that experience no water are advised to boil their water once pressure is restored. The affected customers are those in the upper floors of high rise buildings in Newport and four commercial customers in proximity of the leak.
Repairs will take the better part of the day.
Due to the icing condition at that location, 18th Street is closed in both directions (east and west) between 14th Street and Marin Blvd.