(Read more: Blame Britain's floods on rainfall over Indonesia: Kemp)
Rakow's estimates came after the Association of British Insurers (ABI) put the bill for the damage caused by storms and floodings between 23 December and 8 January at £426 million, with insurers dealing with 174,000 claims for damage.
And as the bad weather continues, there are concerns that flood damage could get worse. Rakow added that if the current conditions persisted into March, the cost for the insurance industry could be closer to £1 billion.
The U.K.'s Met Office issued a rare "red warning" for winds of up to 100 mph in west Wales and north-west England on Wednesday - the first such warning this winter. Meanwhile, the Environment Agency said the River Thames – which flows through London - was set to rise in places to its highest levels for over 60 years.
On Tuesday, Prime Minister David Cameron insisted that, "money is no object in this relief effort. Whatever money is needed for, it will be spent."
(Read more: Severe weather cuts off rail links to southwest England)
While there is no official figure of the total number of evacuations, some areas have seen large-scale evacuations. About 1,000 homes on the River Thames have been evacuated in the past few days, according to the Environment Agency, while Surrey Police said on Tuesday they had carried out 538 rescues since Sunday.
And it's not just households that are being hit, with numerous businesses also being evacuated in Britain.
SunGard, which provides business continuity services during natural disasters, reported that a growing number of customers had utilized their services over the past 48 hours.
"We have customers that have moved away from their day-to-day (location) and are running their services out of our recovery centers - and several others that have put us on alert, or on stand-by," Patrick Morley, SunGard's operations director for Europe, told CNBC.