More frequent extreme weather events combined with less investment in defences would put many more properties in danger by 2035, the document warned.
Details of the report, drawn up in November by the Association of Drainage Authorities, were published by The Observer as parts of the UK prepared for more heavy rain.
The report warned that "failure of assets and networks is more likely as extreme weather events become more frequent and unpredictable".
Referring to spending cuts, it added: "Annual flood and storm damage costs are approximately £1.1bn, 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."
Budget cuts had left local authorities having to reduce funding to organisations and landowners who manage river levels, the document said.
"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," it added.
The Department for the Environment, Food and Rural Affairs (Defra) has said funding is in place for schemes to protect hundreds of thousands of homes.
Meanwhile, it has been announced that more than £40m will be spent strengthening flood defences which were overwhelmed by Storm Eva over Christmas.
A significant portion of that has been earmarked for York, where hundreds of homes were flooded after the Foss Barrier struggled to cope with record levels of rainfall.
Repairs are also expected on defences along the Derwent, Aire, Calder and Ouse in the county - as well as the River Wharfe, which became so swollen that an ancient bridge in Tadcaster collapsed and split the town in two.
The investment is in addition to the £50m pot set aside for local authorities co-ordinating the clean-up effort, and the cash promised to those affected by Storm Desmond in the North West.
The Prime Minister 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.
"We are already spending £280m over the next six years to protect thousands of houses from flooding in Yorkshire as part of our £2.3bn investment to protect 300,000 houses across the country."
Liberal Democrat leader Tim Farron, whose constituency in Cumbria was among those badly hit by flooding, has described the latest package as a "short-term fix", and questioned whether the "small down-payment" of £40m was actually new funding.
An amber "be prepared" warning of heavy rain is currently being enforced by the Met Office for parts of Scotland, with forecasters predicting more than 200mm of rain will fall on saturated ground by Monday.
Yellow warnings are also in place for parts of Wales, Northern Ireland, northeast England and southwest England - with another band of downpours expected on Sunday.
The Scottish Environment Protection Agency has issued 23 flood warnings and three flood alerts, while in England and Wales, there are currently 16 flood warnings and 95 flood alerts.