Queensland flood toll rises to six

Two dead farm workers have been found in a flooded creek, one still inside his car, raising Queensland's flood toll to six.

The men, both Asian, were reported missing four days ago when they didn't arrive at work.

Fears intensified when a car was discovered submerged at Sandy Creek near Gatton on Tuesday.

Police and SES volunteers found another car on Wednesday morning and the body of a 34-year-old man inside.

By the afternoon, the body of his colleague, a 25-year-old man, was found 100 metres away.

Both were swept off the road by rising floodwaters on Sunday morning.

Six people have now died since southern Queensland was hit by severe wet weather from ex-cyclone Oswald on Sunday.

The three-year-old son of two doctors died when a tree fell on him and his pregnant mother while they were looking at flooded areas in the Brisbane suburb of Gordon Park.

His mother, Dr Zara Weedon, remains in a critical condition in the Royal Brisbane and Women's Hospital.

Australian Medical Association Queensland president Alex Markwell has told the Brisbane Times that Dr Weedon and husband Dr Andrew Burke have the sympathy of the entire medical community.

"Dr Weedon and her husband Dr Andrew Burke are well respected and popular members of the medical fraternity and this tragic accident has left us all in great sadness and shock," he said.

The other three flood victims were all men who died in floodwaters - one south of Brisbane, one at Burnett Heads near Bundaberg and the other near Gympie.

More than 200 soldiers have reached Bundaberg where about 2000 homes were flooded, many up to their rooftops.

The floodwaters are slowly dropping but with so much water coming down the Burnett River it's expected to be some time before about 7500 residents can return home.

About 1200 people remain in official evacuation centres, with thousands of others staying with family and friends.

Defence Minister Stephen Smith says defence force personnel will stay in Bundaberg for as long as they are needed.

About 40,000 homes and businesses across southeast Queensland still have no power.

And Brisbane residents have been told to limit water use after flooding forced the shutdown of the city's main processing plant.

The Mount Crosby plant is now operating but residents are still being warned to conserve water.

Water coming into the plant at Mt Crosby had four times more mud in it than during the 2011 flood, authorities said.

Meanwhile, floodwaters are dropping slowly in Logan, south of Brisbane.

Logan Mayor Pam Parker says eight homes in Logan Reserve have had water through them, 7500 are without power, and about 200 residents in the suburb of Buccan are isolated.

A large body of water is heading towards the central Queensland city of Rockhampton with residents preparing for flood peaks to hit this weekend.