Meanwhile, with more heavy thunderstorms predicted through the weekend, property owners cleared damage from the deluge and braced for another potential onslaught.
The breakdown Saturday in the drainage system, which led to the flooding of "a couple hundred" properties, highlighted the challenges posed by New Orleans' aging infrastructure -- a problem mirrored in roads, bridges, water pipes and sewer plants across the nation, Landrieu told CNN.
"Because of the visuals of (Hurricane) Katrina, people keep thinking New Orleans is different than everybody else," the mayor said. "It is absolutely true that the infrastructure in this country is crumbling at a scary pace, and what you just witnessed was infrastructure ... that was unable to keep up with our threats."
Flooding early this year in Houston
and just this week in San Antonio offers proof New Orleans is not the only major city that faces a flood threat, Landrieu said. He drew a distinction between Saturday's rain and 2005's Hurricane Katrina, during which breaches in federal levees led to the flooding of some 200,000 properties.
Pumping out the water
Because of New Orleans' unusual topography -- with many areas below sea level -- it takes about 100 pumps spread across every neighborhood to suck water out of storm drains and canals and push it into a nearby lake or other water bodies. The pumps vary in size and capacity; some are as big as a garage and more than a century old.
Saturday's storms dropped several inches of rain in just a few hours in a handful of neighborhoods. In those places, six of the city's most powerful pumps were offline for routine maintenance or because they'd broken down, said Ryan Berni, the deputy mayor of external affairs.
That meant the system's capacity to drain those areas was cut nearly in half, causing rainwater to pile up like traffic behind a wreck -- and ultimately causing it to push into homes, restaurants and offices, said Berni, whose own home sustained minor flooding.
"We just got really smacked in the wrong place at the wrong time," Landrieu said.
Even so, Landrieu acknowledged that his city's pumps are not all up to par, the result of limited federal funding and a tight local budget. Indeed, the six pumps that were unavailable Saturday -- plus two similar ones in farther flung parts of the city -- are still offline, said Berni, who did not know when they'd be back in action.
More problems, as storms loom
And in yet another setback, New Orleans' Sewerage and Water Board lost service Wednesday night to one of its power turbines, which run the city's oldest and most powerful drainage pumps. It reduced the system's ability to drain street water on the east bank of New Orleans, where areas that flooded Saturday are located, the mayor said.
"The city is urging residents in the affected