Insurance and Savings Ombudsman Karen Stevens said it was important people making a claim didn't throw out damaged items before an insurance assessor had inspected them.
"If they throw those things away it's very difficult sometimes to go back and prove they owned them,'' she said.
"They may not have proof of purchase left and if they don't have the item either, it may look suspicious.''
Ms Stevens said with flooded carpet, many homeowners wanted to immediately rip it up and throw it out, but an assessor would first need to check that it couldn't be salvaged.
"If an assessor doesn't see it they're not quite sure if something is damaged beyond repair or, with the right treatment, could have been sorted out,'' she said.
Homeowners were encouraged to take photographs to clearly document the damage.
Ms Stevens also warned that "inflating'' a claim with items that were not damaged could lead to the insurer refusing the entire claim.
The ex-tropical cyclone Lusi passed over the country during the weekend, causing surface flooding and storm surges, bringing down trees and disrupting power supply.
Civil Defence officials in Auckland said 63 events were reported, including 15 reports of flooding and 35 of wind damage from trees.
Businesses in Paihia, in Northland, were inundated by sea water as the storm surge brought waves over State Highway 11 and into shops and restaurants.
The Insurance Council said it would be a couple of weeks before they could give an indication of the total insurance cost of the storm.
