Three army battalions have been put on 24-hour standby to offer rapid response to flooding as part of what the Government describes as its most comprehensive winter preparedness plan.
The preparations follow a Ministry of Defence review of the handling of devastating floods which caused blackouts and forced people from their homes across the North of England and Scotland last winter.
The battalions - totalling 1,200 troops - will be based in the North, Midlands and South of the UK, throughout the winter months, ready to respond to calls for assistance from Government and local agencies.
Government sources said other elements of the preparations include:
:: The most comprehensive package of NHS resilience ever;
:: Stockpiling of resources to keep roads moving; and
:: Work with the energy companies to keep the lights and heating on throughout the winter.
The Department for Environment, Food and Rural Affairs (Defra) has announced £12.5 million for new temporary defences, including mobile barriers and high-volume pumps, to be deployed at strategic locations around the country.
And the Environment Agency now has four times more mobile flood barriers than last year.
The Army battalions are being trained to assist with the rapid deployment barriers when needed.
Other tasks could include providing engineering and logistics support, and assisting with the evacuation of affected communities.
Cabinet Office minister Ben Gummer said: "We want to make sure that people across the United Kingdom keep safe, warm and healthy this winter.
"That is why we are working together to prepare for all that winter may bring, from providing flu vaccinations to specialist equipment and resources to deal with winter flooding.
"With the army standing by, we have the most comprehensive winter plan yet to keep people safe and the country moving."
In other winter plans, NHS England's flu vaccination programme has started earlier than ever this year, with five million jabs already administered to children aged from two from seven, as well as "at risk" groups such as pregnant women, over-65s and people with long-term conditions.
Gas and electricity supplies are already working to standards set by the National Flood Resilience review.
And on the roads, local authorities and Highways England have stockpiled 1.7 million tonnes of salt - 500,000 tonnes more than in the severe winter of 2010/11.
Environmental campaigners warned putting the army on standby for flooding was no substitute for tackling the causes of worsening floods.
Friends of the Earth climate campaigner Guy Shrubsole said: "The Government's reliance on the military for flood response underlines how much our changing climate has become a national security issue.
"But crisis management isn't a substitute for tackling the root causes of worsening floods: dealing with climate change, investing properly in flood defences and working with nature to slow the flow of water.
"And by failing to do our fair share to cut our emissions, the UK Government is helping to drive floods and extreme weather around the globe - affecting millions of people who lack the resources to prepare for the climate crisis."
Research has found that the extreme rainfall brought by Storm Desmond last December, causing devastating flooding, was made around 40% more likely because of climate change.
Victims and communities hit by floods last winter, in which an estimated 15,000 homes and businesses were flooded, have criticised the Government review which announced the £12.5 million funding for temporary flood defences.
And there have been calls for a rethink of the system for allocating flood defence funding after a Press Association investigation revealed the process could favour richer households and those in parts of the country with higher house prices.
Figures from the Environment Agency for the last six years have revealed the South East got more funding than any other English region for flood protection.