In 2001 1.9 million properties were at risk of floods, the Department for the Environment, Food and Rural Affairs estimates.
However by 2006 some 2.3 million homes were in danger, according to assessments carried out by environment inspectors.
More extreme weather patterns caused by climate change have been cited for an increase in flooding in recent years. Development that fails to take account of flood plains, lack of investment in drainage and paving over gardens has also been blamed.
Floods have hit Britain with increasing frequency, culminating in 17,000 families being forced out of their homes in summer 2007.
Anne McIntosh, the Conservatives spokesman on floods, said the Government has failed to improve flood prevention despite the obvious problem.
"The Government first proposed changes to end the institutional chaos over flood management back in 2005, when will they stop dithering and take action?," she said.
"More and more people are living with the worry that heavy rainfall might flood their home."
The Government is set to respond to the Pitt Review, commissioned after the 2007 floods, in the next couple of weeks.
Ministers are expected to propose a new early warning system, allowing more natural flood plains to take the extra water and more defences.
