The flash floods over the weekend are estimated to have caused more than £5m of claims damage in Portsmouth after a month's rain in just one day, according to loss adjusters.
The city's Southsea area was under up to five feet of water, and flooding, affected more than 20 streets and up to 2,000 residents.
A pumping station was also flooded, leading to the release of untreated sewage.
Fire-fighters, police, the navy and volunteers worked through Friday and Saturday to pump the water and sewage away.
McLarens Toplis marketing director Alex Gargolinski said they had been on stand-by since Friday after a flood watch warning had been issued by the Environment Agency.
Claims were still coming in at the start of the week, but one estimate put the total damage at more than £5m. Large claims received so far include more than £500,000 from a school and £100,000 from a leisure centre.