NEW ORLEANS (AP)  Mayor Mitch Landrieu says New Orleans' most widespread boil-water advisory since Hurricane Katrina will continue at least until 3 p.m. Sunday, because that's how long it will take to test for bacteria. The advisory covers most of the city, affecting more than 300,000 people. Landrieu says crews took water samples from 28 spots around the city's east bank — but the samples need 24 hours to incubate. Officials say the boil advisory was called as a precaution after a power failure late Friday at the city's main treatment plant — including its three backup power systems — caused low water pressure throughout the east bank. Electricity was restored around midnight, and water pressure is back to normal. The city's west bank was not affected. Copyright 2010 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed. Guidelines: You share in the USA TODAY community, so please keep your comments smart and civil. Don't attack other readers personally, and keep your language decent. Use the "Report Abuse" button to make a difference. You share in the USA TODAY community, so please keep your comments smart and civil. Don't attack other readers personally, and keep your language decent. Use the "Report Abuse" button to make a difference. Read more