MELBOURNE - Australia reported the first fatality from days of widespread flash flooding on Saturday, despite heavy rains easing and flood levels topping out across much of the southeast.

Hundreds of homeowners began a long clean-up after storm waters engulfed streets, houses and cars across three states, with Melbourne suburbs among the worst hit.

Two very wet years have left much of eastern Australia sodden, and floods now frequently follow even moderate downpours.

"It was frighting. I've been here for the other floods but I've never seen anything like that," 61-year-old Antoinette Besalino said.

The apparent flooding victim was a 71-year-old man who was "found deceased in floodwaters in the backyard" of his property in the town of Rochester, a small town north of Melbourne.

"Crews are on scene and police are attempting to get to the property, which is currently blocked off due to floodwater," police said. "The exact circumstances surrounding the death are yet to be determined."

As the waters ebbed, residents were left wading through mud-caked streets, passing collapsed fences, abandoned cars, tree branches festooned with debris and, in one instance, a marooned wheely bin.

"The cleanup is going to be huge," said 58-year-old Peter Dimauro. "Think about all of the branches and all of the garbage that has washed up."

About 466 homes have "above-the-floor flooding", according to Victoria state premier Dan Andrews. "Almost certainly those numbers will grow as we see flood waters peak in a number of communities," he said.

For some, the risk is not yet over, with water still funnelling into already-swollen catchments. Evacuation orders remain in place for dozens of communities.

"This is serious, this is potentially very very dangerous," said Mr Andrews.

Australia's east coast has been repeatedly lashed by heavy rainfall in the past two years, driven by back-to-back La Nina cycles.

The east coast flooding disaster in March - caused by heavy storms in Queensland and New South Wales - claimed more than 20 lives.

Tens of thousands of Sydney residents were ordered to evacuate in July when floods again swamped the city's fringe.

Climate change does not cause La Nina events, but scientists believe it could make periods of flooding more extreme because warmer air holds more moisture. AFP