NEW ORLEANS (AP) -- Taps in New Orleans briefly went dry Sunday after a boiler's heating flame went out of control in the plant supplying electricity for the city's water treatment.

Marcia St. Martin, executive director of the city's Sewerage and Water Board, said the outage lasted less than 20 min Sunday morning. Twitter came alive with residents bemoaning the loss about 9 a.m. Central time, and Mayor Mitch Landrieu tweeted to his followers that the city was looking into the matter.

Martin said the loss of pressure opened the way for possible contamination, and water samples are being taken citywide.

She said all sample collection should be complete by Sunday afternoon, and results should be available about 24 hours later. It takes that long to detect the presence of potentially dangerous bacteria.

Officials have advised more than 300,000 residents on the Mississippi River's east bank to boil water for drinking, brushing their teeth or preparing food for at least 24 hours.

Most of New Orleans, including the French Quarter and Central Business District, is on the east bank. The treatment plant there provides about 135 million gallons of drinking water a day, compared with 11 million from the west bank treatment plant.

In October, a similar problem occurred at the east bank plant. City officials were criticized because they did not put out a notice that tap water might be contaminated until four hours after the plant shut down. A power problem in November 2010 also created similar conditions.

Across the city Sunday, some residents and businesses readied water supplies to use under the boil advisory. At Zeus' Place, a pet boarding and daycare business, owner Michelle Ingram said she was using bottled water for the 80 dogs and 7 cats there.

"We were sitting on 20 gallons of water and I just got 21 more," she said. "Which should last us through tomorrow afternoon -- and hopefully we'll know then whether or not the boil water order is still on."