Spokesman Stephen Bell said some streets in Wollongong were in a "high risk flood zone" and, though there were options for home owners to negotiate, flood mitigation works on local infrastructure were the most effective.

"There are ways we can work with customers to help them manage larger premiums or premium increases, including ensuring they are receiving all the appropriate discounts, looking at their excess and so forth," he said.

"The best way to manage the costs longer term, though, is to ensure as much as possible is being done to manage the level of risk in the first place - flood mitigation strategies, a carefully considered approach to planning and developments."

GIO is owned by the Queensland-based Suncorp, which was exposed to significant payouts after the 2012 floods in that state.

Mr Bell used the example of the Queensland town of Roma, where a 5.2 kilometre levee bank up to four metres high has been built to withstand a 1-in-1000-year flood.

It cost $16 million, which came mostly from Queensland's Resources for Regions fund.

"[The] levee built in Roma earlier this year has reduced premiums by up to 90 per cent and, on average, 60 per cent," Mr Bell said.

"The investment into a flood levee built in Grafton in the 1970s has returned more than $100 million in economic benefit, including a reduction in the risk for home owners and the subsequent reduction in their insurance premiums.

"When risk comes down, so too does insurance."

He responded to the Mercury's questions - focused on Northview Terrace, Figtree, and Hewitts Avenue, Thirroul, by saying those streets were in a "high risk flood zone".

"Following the 1998 floods, a number of insurers introduced flood cover on their policies, including GIO," he said.

"Wollongong is a beautiful city, but that combination of escarpments, creeks and flood plains does make for a lot of flooding and flash-flooding risk, as we have seen in recent years.

"And the costs of insuring homes in high flood-risk areas is significant in recent years across the country.

"The data we use to determine the flood portion of the premium is worked out for each individual address, as opposed to a suburb or postcode approach.

"Our view of flood risk changes over time as new information and data becomes available.

"It is a combination of our own flood claims experience, flood data from the council and the National Flood Information Database."

Wollongong City Council infrastructure and strategy manager Mike Dowd said consumers should shop around.

"Insurance companies determine their own insurance premiums, independent of council," he said.

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