State Premier Campbell Newman said the bill had already topped A$2.4 billion ($3 billion) and was still climbing, exceeding the A$2.38 billion impact of 2011.
Insurers estimate the cost of the almost 26,000 claims received so far at A$290 million.
Newman said a permanent fix was needed to protect communities from regular floods and other disasters.
"We can't accept that our communities can be flooded every couple of years," he said. "We can't accept that's how life has to be lived."
Newman warned the cost would be huge, requiring a wide range of measures including the rethinking of developments, relocating parts of some towns, new levees and more flood mitigation dams.
The full scale of the week's inundation is only now emerging as waters recede and roads reopen, allowing access to areas isolated by floodwaters.
Some areas remain at risk. At Rockhampton, 600km north of Brisbane, the Fitzroy River was expected to peak at 8.5m late last night, below the 2011 peak but likely to affect more than 1000 properties.
Water was rising in some suburbs late yesterday, but authorities were hopeful most homes would escape.
The Condamine River was also still rising, cutting off the Western Downs town of Condamine. The small communities of Toobeah and Bungunya, near Goondawindi on the NSW border, were also isolated.
In Bundaberg, the worst-hit area where about 2000 homes were flooded, some residents were yesterday allowed back to devastated areas of the city's north as waters receded.
Access remained difficult and limited, with roads severely damaged. On one road floodwaters had gouged a 100m-long trench, 2m deep.
Power, water and sewerage had been cut, with no indication of when they would be repaired.
A packed town meeting yesterday was told that 10 properties in the area had been destroyed and about 30 severely damaged.
Bundaberg Council chief executive Peter Byrne said damage was severe, with one home washed onto the road and another missing.
"What I'm saying to you the gravity of the situation is dire," he said.
Journalists from Brisbane's Courier Mail, allowed into the stricken suburbs under police escort, described scenes of devastation: homes wrecked, some ripped from their foundations, and cars and trucks trapped in a quagmire of mud.
One weatherboard house had been driven 400m down the street and wrapped around a power pole. All that remained of others were brick remnants. A church had also been destroyed.
Southwest of Bundaberg, the town of Gayndah remained without power.
At Gympie, 160km north of Brisbane, residents and business owners returned yesterday to survey damage after about 150 properties were flooded when the Mary River broke its banks.
The Queensland Farmers' Federation estimated the losses at A$100 million across crops, sugar, cotton, orchards and dairy and pig farms.
Chief executive Dan Galligan warned disaster aid was inadequate and many farmers could not recover, causing severe and prolonged economic impact on communities already battered by natural disasters.
