The Government has defended its funding of flood defences after it emerged ministers were told spending cuts could leave 240,000 extra households facing a "significant risk" of flood damage within 20 years.
A document presented to ministers in November last year - just days before Cumbria was inundated - warned of the risks posed by extreme weather events becoming more frequent.
The Department for Environment, Food and Rural Affairs (Defra) said the document was outdated because the flood defence budget had been increased in the Autumn Statement.
Details of the paper drawn up by the Association of Drainage Authorities (ADA) were reported in the Observer as more heavy rain hit the UK and David Cameron announced a £40 million package to bolster defences in areas hit by Storm Eva.
The ADA, which represents a range of organisations responsible for managing water levels, said in the document: "We have had the five wettest years since 2000. The Environment Agency's funding for maintaining flood assets has fallen by 14%. Downward adjustments have also been made to intended revenue spending commitments."
It warned that "failure of assets and networks is more likely as extreme weather events become more frequent and unpredictable" and recommended a change in approach to a more long-term strategy.
Referring to the potential impact of spending cuts, the document said: "Annual flood and storm damage costs are approximately £1.1 billion, according to the Association of British Insurers, and those households at significant risk (of flood damage) through a reduction in our capacity to manage water levels could increase from 330,000 today to 570,000 in 2035."
The document said cuts to local authority budgets had left them with little option but to reduce funding to drainage boards and other organisations and landowners who manage river levels, the Observer reported.
"Such reductions in investment mean that some river, watercourse and sea defence systems and structures are maintained only to a minimal level; consequently the useful lives of those assets will be reduced," the paper said.
"The rivers and coasts of some rural areas are at a major crossroads and their funding is purely based on the benefits of flood risk to people and property as calculated currently. The Environment Agency has ... reduced the extent of their watercourse channel maintenance and taken steps to stop operating a number of structures and systems. Examples include lowland catchments across Lancashire and Cumbria."
A Defra spokeswoman said: "These claims are simply not true. This document was written before last Autumn's Spending Review, in which we increased flood defence spending to £2.3 billion by 2021.
"And we're spending more on flood defences in this parliament than in the last, by building 1,500 new flood defence schemes that will better protect 300,000 more homes, which itself is more than was spent in the parliament before that.
"No other Government has ever made such a long-term commitment to fight floods and help protect our most at-risk communities and we can only afford to increase flood defence spending because we're building a stronger economy."
Mr Cameron announced that £40 million would be spent on fixing and bolstering flood defences battered by Storm Eva.
Charities raising cash for communities left devastated over Christmas by the deluge will be matched by the Government up to a total of £2 million in a move echoing pledges to earlier flooding victims.
Thousands of homes and businesses across large swathes of northern England were hit by severe flooding as the storm wreaked havoc on Boxing Day.
Mr Cameron said: "I have seen at first-hand the devastation caused by flooding. And that's why this work to repair and improve flood defences is so vital."
Around £10 million of the funding package will be used to improve defences in York after they failed to cope during the storm. Environment Agency officials decided to lift the Foss Barrier designed to protect the city after finding its pumps were at risk of electrical failure due to water entering the building, prompting widespread anger among residents.
The rest of the cash will be spent on repairing defences on the Calder, Aire, Ouse and Derwent rivers in Yorkshire as well as the Wharfe, which runs through Tadcaster where the storm left the town split in two when an ancient bridge collapsed.
Mr Cameron has also made Transport Minister Robert Goodwill a "flooding envoy" for Yorkshire to oversee the response in the region and identify what must be done to protect the area in the future.