One in six homes in England is at risk of flooding and some £20 billion is needed by 2035 for defences to protect properties from rising sea levels and extreme rainfall, the Environment Agency warns today.

Spending on flood defences must rise from £570 million a year to £1 billion a year — and that will protect only 490,000 homes that are at the highest risk of flooding.

The threat to entire communities is particularly alarming as vital installations for electricity, water and gas are at significant risk of flooding, which could switch off taps and leave thousands of homes and buildings without light or heating, the agency warns.

Thousands of schools, nurseries, hospitals and GP surgeries are also at very high risk of being swamped by floods — but rescue operations could be thwarted because of the high number of emergency services such as police, fire and ambulance that are also at risk from flooding.

Some 2,500km (1,550 miles) of railway, 4,000km of roads and scores of premises earmarked for use as flood evacuation centres are also threatened as are hundreds of seaside camping and caravan parks and prisons.

Ministers have already made clear that the taxpayer cannot foot the bill to protect every property from flooding. The area around Boston in Lincolnshire, identified as the highest flood risk in England, has 23,700 properties under threat and extra council tax levies are likely to be necessary.

In areas with a small number of dwellings requiring defences costing £50,000 to £100,000, homeowners may have to pay for it themselves.

In a swath of southern England, which has 111,356 properties at risk — including houses, offices, factories, warehouses, farms and other commercial premises — some hamlets and neighbourhoods may be expected to raise their own funds for flood defences. The suggestion that “beneficiaries should pay” in certain settlements was accepted by the Government last year. Developers building new homes and towns are already being made to address issues of flood risk as a requirement of planning permission.

The Environment Agency believes that householders should be given incentives to floodproof their homes in return for cheaper premiums for insurance cover. It is also urging local authorities to offer council tenants the chance to pay for flood insurance cover for their belongings as part of their rent.

Conservation work that is funded by lottery money could be extended to help save special heritage sites, beauty spots and important wildlife and scientific sites from flooding.

The flood threat to homes and business is enormous — with a total of 5.4 million at risk of flooding, of which 2.4 million are threatened by rivers and sea and a further 2.8 million from surface water from overflowing drains. Almost half a million are rated as being at the highest risk but without extra cash on flood defences an extra 350,000 properties, including 280,000 homes, will be in that category within 25 years.

Some £150 million a year is also needed to improve drainage systems and remove the threat from surface water that devastated so many places in the freak summer flooding two years ago, which claimed 13 lives and flooded 55,000 homes, in the South West, the Midlands and Yorkshire.

Without the extra investment the cost of flood damage to properties is also estimated to rise from £2.5 billion a year to £4 billion by 2035.

Nick Starling, director of general insurance at the Association of British Insurers, said insurance companies were willing to play their part to help households. “It is vital that Government now sets out a long term strategy for dealing with this increasing risk,” he said.

Times recommends

• Energy-saving ideas from switched-on professor
• Rooks are as clever with tools as chimpanzees
• Burping of the lambs blows roast off menu