Homeowners living near rivers and the coast face losing up to 40 per cent of the value of their homes as flood risk makes them uninsurable.
More than a million homes and 300,000 businesses are at risk, including those in parts of London, Southend, Brighton, Reading, Birmingham, Nottingham, Liverpool, Manchester, Hull, Middlesbrough, Blackpool, Glasgow and Edinburgh, the Environment Agency says.
The insurance industry points to evidence that climate change and rising sea levels will increase the likelihood of floods. It has an agreement with the Government – which runs out in 2013 – committing it to provide cover for customers, as long as flood risk is properly managed.
Insurers are expressing concern about cuts to investment in flood defences implied in the coalition's Comprehensive Spending Review, and the affect of funding cuts on extending the agreement – the UK is currently one of the few countries to provide flood coverage automatically through property insurance.
Nick Starling, of the Association of British Insurers, said: "We must ensure that our spending on flood defences and flood management is targeted to those areas where it is needed the most, and that the Government implements a long-term flood management strategy."
Flooding is expensive for insurers, with claims typically between £20,000 and £40,000. In the past decade insurers have paid out £4.5bn to customers whose homes or businesses have flooded, three times the £1.5bn paid in the previous decade.
Under the spending review, the Department for Environment, Food and Rural Affairs took a 29 per cent budget cut, including £110m from planned spending on new flood defences. Defra insists flood risk management is a "priority".
Some 20,000 families in Essex coastal areas say they have lost equity and are struggling with increasing premiums. Essex County Council has approached the Government for £20m to build a sea wall to protect 35 high-flood-risk homes at Great Wavering. The Environment Agency has completed 160 flood schemes defending 160,000 properties since 2007.
Dr Paul Leinster, its chief executive said: "We will continue to reduce flood risk by investing in defence schemes, but it is essential that people are all also better prepared, by signing up to the Environment Agency's flood warning service and rebuilding damaged properties to make them more flood-proof."
'It'll be harder to sell now'
Wot Blowers, 62, a self-employed gardener from Cockermouth, Cumbria, was rehoused through her insurance company following floods in the county in 2009
"It was awful. I was out of my home for nearly a year. I am back now, but it has taken the best part of a year to get the house fixed. The whole of the ground floor was flooded halfway to the ceiling.
"I probably have lost value on my house. I've been wanting to sell it for years, but it's going to be a lot harder now. My premium was £150 originally, but when I got my insurance renewal it was £2,111. I spoke to Trading Standards, but it's still higher than it was."