Questions are also being asked about Wollongong City Council's flood studies, with many "high risk" areas not touched by Monday night's floodwaters, while areas mapped as getting only 15 centimetres of water were badly damaged.

Some of these places on Lachlan Street have been flooded many times since 1998.

Meanwhile, properties further downstream, which have been mapped as being under one or two metres of water in a serious flood, escaped without any flooding at all.

All flash floods are different, but some residents are wondering why the council's focus is on drain blockage studies, which take years, rather than more effective flood-mitigation works.

Some residents have been arguing for years that drains becoming completely blocked are not the problem most likely to cause flood troubles in Wollongong.

Instead, they say the creek system that Wollongong relies on to drain floodwaters is too often overgrown, clogged or being forced to follow an unnatural path.

For its part, Wollongong City Council pointed out that it had done flood mitigation works on the Lachlan Street culvert, works that involved widening the space underneath it to help prevent it becoming blocked.

The council's position is that creeks classed as being private property are not its problem.

Jannine Vincent's Lachlan Street house has flooded many times in the heavy rains brought by east coast lows - this time around, she watched garden furniture floating past her in waist-deep water.

"This is the third time that we've had a river come through the backyard," she said.

But the latest review of the council's Hewitts Creek flood study, prepared by consultants and finalised this month, has her property copping only a few centimetres of water in a massive 100-year flood.

"They say we're doing studies, but it will take years ... but nothing ever happens," Ms Vincent said.

"I think they actually need to get real ... and listen to what the landowners are saying."

Her property is beside a sharp bend where the narrow Hewitts Creek has been forced into an unnatural path, and when the water rises, it simply eases over the bank.

The council's manager of infrastructure strategy and planning, Mike Dowd, said the council had been active in flood mitigation works near Lachlan Street.

"Council has recently completed a number of flood mitigation works, including works on the Lachlan Street culvert," he said.

"These works were designed to increase the hydraulic capacity of the culvert under Lachlan Street.

"Council's floodplain management role is to identify flooding risks, mitigate and manage those risks, however, council's role is limited as we cannot undertake work on private property."

This is little comfort to Barb Hunt, who lives in Lawrence Hargrave Drive.

She has a swimming pool the colour of mud caused not by blockage from the railway bridge, as flood maps predict, but water flowing east from the road.