The water distribution system was cut off for approximately 20 minutes Sunday morning and the boil-water alert for the city's east bank was in effect for 24 hours, the (New Orleans) Times-Picayune reported.
Marcia St. Martin, executive director of the New Orleans Sewerage and Water Board, said no one was injured in the small fire that began in the plant's boiler room.
She said the outage caused water pressure to drop below federal governmental safety standards, which could allow bacteria to enter the system.
"It took a few minutes to determine the extent of the damage. But within about 15 minutes we were able to identify the possibility of needing a boil-water advisory," St. Martin said.
Workers were able quickly to switch to an alternate electricity source and regain safe pressure levels, she said.
She said the decision to issue the boil-water alert was made within a few minutes, in contrast to the 4-hour pause after a similar pressure drop last year for which city officials took criticism.