There is no clear guess at the overall cost of the damage, but it is estimated to run into billions of dollars, and insurers have already received 31,000 claims from the region and flood-hit northern NSW.
Brisbane Lord Mayor Adrian Schrinner urged people to enlist for the Mud Army 2.0 to help clean up in the state capital, where there is a major flood after 795mm rain fell in just three days.
With 15,000 homes and more businesses damaged, many Brisbanites are keen pitch in again like they did with first Mud Army after floods 11 eleven years ago.
"I have revived the renowned Mud Army from the 2011 flood so we can coordinate the clean up together and ensure people don't get left behind," Cr Schrinner said.
"If you helped out in 2011 or have just heard the stories about the heroic efforts of hundreds of Brisbane locals I am urging everyone willing and able to sign up to get involved."
In Gympie, north of Brisbane, floodwater filled the Bank of Queensland branch to the ceiling as the Mary River peaked at 23 metres on Monday.
Neighbouring businesses on the town's main street also went under with water receding enough on Tuesday for owners and staff to inspect the damage.
"It's going to be a complete rebuild at this stage," BOQ manager Jellina White told AAP on Tuesday.
"Even though it's a bomb site, at least we sort of can get in and feel like we're actually doing something at the moment.
"We put everything up as high as we can and then for it to go to 23 (metres)... pretty much just everything went underwater."
On the Fraser Coast, Maryborough is cleaning up after the Mary River peaked at 10.3m, one metre below the flood levee, on Monday night.
It was the city's second major flood in two months, but this time the CBD stayed dry after it was inundated in January when an underground stormwater valve failed, sending water up through drains.
Local MP Bruce Saunders said there was an "eeriness" as residents waited for the river to rise, but volunteers were already out cleaning up during the "resilience phase" on Tuesday.
"The community spirit here, to get the city back up on its feet, is second to none," Mr Saunders told AAP.
In Ipswich, more than 150 residents remain stranded in low-lying pockets of Goodna as the floodwaters slowly recede.
Councillor Paul Tully said some people remain trapped without electricity or food with boats the only way in or out.
He said reports of looting across have also infuriated Goodna residents who were forced to evacuate.
"Sadly we have had looters. They've broken into cars and people's homes before people even get a chance to look at the damage," Cr Tully told AAP.
South of Brisbane, another 200 homes have been inundated at Logan, according to Mayor David Power, and the suburbs of Flagstone, Jimboomba and Logan Reserve remain cut off.
"We've got around 200 roads across the city that are either closed or affected by floodwater," Cr Power said.
"Some will be closed for days as water recedes and Council engineers can conduct safety inspections."
The federal government has also extended grants of up to $180 per person, to a maximum of $900 for a family of five or more to eligible people in flood affected areas across the southeast.
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