One expert says it could take a month or more to pump all the water out of New Orleans.
Lt. General Robert Flowers used to head up the Army Corps of Engineers, the group that's working on the problem now.
Flowers says it all depends on how much of the pumping system can be dried out and repaired quickly. Most likely, he says the draining of New Orleans will have to start slowly and will probably take a month or more.
So far, the Corps of Engineers working in New Orleans has said there's no way to know exactly how long it will take to drain the city. Officials say there are a number of factors, including how much rain falls on the city in the meantime.