Some 25,000 body bags have been sent to the New Orleans area, as authorities begin to recover the dead in the city.
The official death toll stands at 83 in the city, including 30 elderly people found in a flooded nursing home. But thousands are feared to have died.
Bodies remain in the stagnant flood waters as health fears grow for up to 10,000 people still in the city.
Three people are also known to have died from contaminated flood water, in the aftermath of Hurricane Katrina.
They are believed to have contracted infections after coming into contact with cholera-related bacteria.
New Orleans' mayor has ordered the forced evacuation of the city, which used to have a population of 450,000.
A temporary morgue in a town about 70 miles (113km) away is preparing to handle 5,000 corpses.
A state health official told the Associated Press he did not know how many bodies to expect.
The mayor of New Orleans, Ray Nagin, has said the death toll could reach 10,000.
Fuel and sewage
Police and soldiers have been going from house to house to encourage those still in the stricken city to leave.
Many householders are fearful of losing their possessions if they go, after reports of widespread looting.
"I haven't left my house in my life," 86-year-old Anthony Charbonnet told AP.
"I don't want to leave."
The BBC's Daniela Relph in New Orleans says police do not want to drag people out - but warn that they are prepared to do so in the face of a growing public health risk.
As water is pumped out of New Orleans, the diminishing flood reveals dead bodies, raw sewage, fuel and rusting vehicles.
The US Environmental Protection Agency says the floodwaters contain unsafe levels of E.coli and other bacteria as well as high levels of lead.
The city's authorities have urged anyone left in the city to avoid all contact with water.
"This water is not going away any time soon," disease control official Julie Gerberding told reporters.
US Vice-President Dick Cheney is due to visit the region hit by last week's hurricane.
More than 110 people are known to have died in the state of Mississippi. Hundreds of thousands from the devastated areas are living in temporary shelters in Texas and other states.
President George W Bush is to ask Congress for an extra $51.8bn to fund relief efforts.
The money - on top of $10bn that has already been granted - is destined for rescue efforts, clean drinking water, and public health needs.
Presidential and Congressional plans for inquiries into how the disaster was handled have been questioned by the opposition Democrats, who have raised the idea of an independent commission.
President Bush said on Tuesday he would lead an investigation himself as two Senate committees began separate inquiries.
Meanwhile, it has emerged that some 400,000 jobs could be lost this year because of the hurricane.
The Congressional Budget Office estimate comes as the economic impact of Katrina is put at more than $100bn (£55bn).