Thousands of health centres and doctors’ surgeries, schools and miles of railways and roads are also at risk, according to the agency’s Flooding In England report.
Almost half a million homes, offices, factories and warehouses are at a significant risk of flooding from rivers or sea, with a greater than one in 75 chance of being flooded in any year.
The highest number of properties at significant risk are in the south-east of England, where 111,356 are threatened with flooding.
Boston, Lincolnshire, has the greatest number of properties at high risk – 23,700 – of any local authority.
According to the latest analysis of the impacts of climate change on the UK released this week, the risk of flooding is set to increase due to rising sea levels, more rapid coastal erosion and increasingly severe and frequent rainstorms.
Without an increase in investment in flood defences, an extra 350,000 properties, including 280,000 more homes, will face a significant risk of flooding by 2035, bringing the total to 840,000 under threat, the EA said.
Funding for maintaining and constructing defences will need to double from £570m in 2010/11 to more than £1bn in 2035 to safeguard the same number of properties as are currently protected, the Environment Agency said.
Approximately £150m each year will be needed just to address the risk of surface water flooding, which caused some of the problems in the devastating 2007 floods, the agency said.
In the floods two years ago, which hit parts of Yorkshire, the Midlands and the south-west of England, 13 adults died as well as two premature twins, while 55,000 properties were flooded and thousands had to be rescued from the flood waters.
Without increasing funding for defences, the annual cost of damage to residential and commercial properties could rise from £2.5bn to £4bn, the agency warned as it released its long-term investment strategy for England.
The Environment Agency’s chairman Lord Chris Smith said: “The latest climate change data shows that the risk of flooding and coastal erosion will continue to increase in the future due to rising sea levels and more frequent and heavy storms.The Environment Agency has completed 90 flood defence schemes in the past two years, providing increased protection to over 58,000 properties.”
The Environment Agency said more than 430,000 people in flood risk areas had signed up to its free warning service, which provides alerts by text message, telephone or email, and urged those who have not subscribed to join.
The environment secretary, Hilary Benn, said: “We have invested record levels of funding in recent years but, as the UK climate projections we published yesterday make clear, climate change means all of us will need to do much more in the future to adapt and manage the risks of flooding and erosion.”
The shadow environment secretary, Nick Herbert, said: “The Environment Agency’s call for more investment in flood defence brings home the reality of climate change, and there will need to be a debate on the priorities, but the public must be protected.
“When a staggering one in six homes in England are at risk, it is essential that flood defence schemes are cost-effective and delivered on time, and that no unnecessary development takes place in areas that are susceptible to flooding.”
In April, the Environment Agency and Met Office opened a new £10m Flood Forecasting Centre to provide earlier and more accurate flood warnings.
English regions ranked in order of the number of properties at significant risk of flooding:
South-east England: 111,356
South-west: 86,178
East Midlands: 81,096
Yorkshire and Humber: 65,380
Greater London: 40,412
East of England: 33,050
North-west: 28,941
West Midlands: 19,173
North-east: 19,167
Total: 484,753
Top 10 local authorities with the highest number of properties in areas with a significant chance of flooding:
Boston district: 23,700
North Somerset: 20,415
East Lindsey district: 14,949
Windsor and Maidenhead: 11,477
Kingston upon Hull: 9,825
Shepway district: 9,065
Sedgemoor district: 8,092
East Riding of Yorkshire: 7,513
Runnymede district: 7,007
Warrington: 6,533