Residents returned to parts of Australia's third-largest city on Friday to begin the enormous task of cleaning up after flood waters that had swamped whole neighbourhoods began to recede.

Garbage trucks circulated through streets in Brisbane that were lined with putrid mud, while some residents dragged waterlogged furniture out of damaged homes.

Upstream of the city, soldiers fanned out to poke through debris in the search for more victims.

Deadly floodwaters are finally beginning to recede in the state of Queensland, but residents face months, if not years, of reconstruction efforts that will cost billions of dollars.

In total, 25 people have been killed since flooding began in late November, and another 55 people are still missing.

Officials have warned the death toll will likely rise as rescue workers reach submerged cars and houses as the waters recede.

"Queensland is reeling this morning from the worst natural disaster in our history and possibly in the history of our nation," Queensland State Premier Anna Bligh said Thursday.

In one of the latest deaths, a man was killed after being sucked into a storm drain while inspecting his father's property. Two other bodies were also found on Tuesday.

The highest concentration of casualties was in Toowoomba earlier this week, when a flash flood washed away cars and homes and killed at least 14 people -- with two new bodies found on Thursday.

Toowoomba's Deputy Police Commissioner Ian Stewart warned that rescue workers are only now reaching some of those affected.

"We've got to brace ourselves for more bad news," Stewart said.

Brisbane, a city of two million people and the state capital, saw the most widespread damage to property.

Some 30,000 homes and businesses were flooded in the city as the Brisbane River overwhelmed its banks.

Mayor Campbell Newman said 11,900 homes were completely inundated along with 2,500 businesses. Another 14,700 homes and 2,500 businesses were partially flooded.

In some low-lying areas, flood waters were as high as traffic lights, and reached the roofs of some buildings.

While many residents were told it would be days before they could return to their properties, others were told the damage was so extensive they may never again be able to live in their homes.

"It is a very, very monumental task that we're facing," said freelance journalist Steve Molkentin.

"There are houses that have been simply picked up by the floodwaters and moved kilometres downstream ... houses that are up trees, places they shouldn't be, so there are people that will be displaced for a long time."

Molkentin said some people are beginning to make their way back to their properties and dealing with the "gut-wrenching" reality of the damage.

"For those that have houses they can come back to, they're expecting it's going to be at least a couple of months before they're going to be inhabitable."

Across Queensland, about 60,000 homes were without electricity on Friday after electricity providers switched off power due to the risk of electrocution.

Railway travel was also on hold, roads and bridges were washed out, and many residents used boats, kayaks and even surfboards to get around.

The damage, though widespread, could have been worse. In Brisbane, the floodwaters crested at 4.45 metres, about one metre less than expected.

"That means there wasn't quite the devastation we were expecting but definitely there are still thousands of people and thousands of homes still underwater and still affected," Molkentin said.

Officials are still trying to get a grip on the extent of the damage. Before the floodwaters hit Brisbane, the damage was already pegged at $5 billion.