ICA Communications Manager Campbell Fuller told AAP the movement of the water during the flood was similar to that of ex-Cyclone Oswald, which caused $1.26 billion of damage in Queensland and northern NSW in 2013.
He rejected warnings from Townsville Mayor Jenny Hill that north Queenslanders would not accept unfair premium rises following the floods.
"Right now we're focused on fixing properties," he said.
"Any talk of premium rises is premature."
Cr Hill urged insurance companies to process claims quickly to help residents get back on their feet.
"The recovery effort is going to take some time, but the job becomes that much easier when insurance companies act as responsible corporate citizens," she said.
The ICA said insurers in Australia have used a standard definition for flood since 2012, which includes water escaping from a dam, including an intentional release.
Meanwhile the federal government has relaxed the rules on who can access disaster funding following Prime Minister Scott Morrison's tour of flood-struck Townsville.
Previously, residents could only apply for federal government relief if they suffered damage to at least 25 per cent of their homes but that rule has been abolished, and they can now apply if water has gone over floorboards in their house.
"After seeing firsthand the challenges faced in Townsville yesterday, I asked for changes to be made last night to the eligibility for the disaster relief payment," Mr Morrison tweeted on Wednesday, less than 24 hours after visiting the city.
The Queensland government has also kicked off a flood appeal with a donation of $200,000.