Flood ravaged areas of England are being warned that more heavy rain is set to sweep across the country.
Hundreds of families are still unable to return to their homes as floods continue to affect parts of Yorkshire and the Midlands.
But the risk of a breach in a dam wall that threatened villages in Yorkshire has been "significantly reduced".
The floods have claimed four lives including a 14-year-old boy and a county court judge from Worcestershire.
The Queen has expressed her shock at the devastation caused by the flooding. She said her thoughts were with people who had lost family, friends and homes.
The floods have been most severe in Yorkshire, Lincolnshire and the Midlands.
The Met Office has issued an early warning of severe weather, with further rain and showers forecast to sweep across parts of the UK later this week and through the weekend.
In South Yorkshire, army personnel moved sandbags in to reinforce the bank of the River Don after it burst its banks. An RAF helicopter helped to shore up another part of the overflowing river.
Hundreds of families in the area remain in temporary accommodation.
But the search for a man reported to have fallen into a flooded drainage dyke near Doncaster, South Yorkshire, has been called off.
Police divers searched the water course after a woman reported hearing a man shouting for help, but found nothing. Nobody has been reported missing.
In other key developments:
Dozens of people have been moved out of their homes in the village of Toll Bar, near Doncaster, and locals say the water has continued to rise
Firefighters have rescued 25 people from cottages in the village of Powick, near Worcester, overnight
Residents of Bransby, Lincs, have been evacuated to Lincoln College, joining 20 people who spent the night there
A huge operation has been undertaken to pump out water from the reservoir behind Ulley dam, South Yorks, and reinforce the embankment.
A crane was used to lift sandbags near the Ulley dam
South Yorkshire Police said the M1 had reopened as a result but warned it could be closed again at short notice if the risk from the dam increased.
Some evacuated residents from the villages of Whiston and Treeton were told they could return to their homes because the risk of the dam bursting had receded; others were told to stay away.
The Association of British Insurers says the overall cost of the floods will run into hundreds of millions.
They urged ministers to improve flood defences and warned that about one in four people did not have contents insurance, so would not be covered for flood damage.
Ministers have offered emergency aid to the worst affected areas to help with the cost of the clear-up.
UK TRANSPORT UPDATE
The M1 in South Yorkshire was closed early on Tuesday and reopened on Wednesday afternoon
A1 in Newark closed in both directions
Network Rail says services including the east coast mainline are fully open but subject to some disruption
In a message issued to 11 Lord Lieutenancy offices, the Queen expressed her admiration for the emergency services, the local authorities and volunteers "working tirelessly to help those affected".
She expressed her "heartfelt thanks" to everyone concerned with the relief efforts.
And Clarence House said the Prince of Wales will visit some of the flooding victims on Friday when he is due in the Peak District for a series of engagements.
David Rooke, head of flood risk at the Environment Agency, said on Monday morning the situation was "still very difficult" in parts of Yorkshire and the Midlands.
"But the situation is improving, river levels are dropping and obviously a massive clean up is under way," he said.
Baroness Young, the head of the Environment Agency, has blamed inadequate funding for the agency's failure to get the country's flood defences ready to cope with the rainfall.
She told MPs on the Commons public accounts committee that she rejected the charge that she had "manifestly failed" and should consider resigning.
In Sheffield, most of the people in emergency shelters have returned home but they face temporary power shutdowns as electricity supplies are restored.
On Monday, a pensioner died after he was caught in rising floodwater in Sheffield. He was named by South Yorkshire Police as Peter Harding, 68.
In a separate incident in the city a 14-year-old boy, named as Ryan Joe Parry, was killed after falling into the River Sheaf at Millhouses.
A third person, Mike Barnett, 28, died after becoming trapped in a storm drain in Hull.
The fourth victim of the flooding, Eric Dickinson, 68, was swept away by rising flood waters in Pershore, Worcestershire.
A search had been launched for Mr Dickinson, a county court judge, who lived in Leigh, near Pershore, after he telephoned his wife on his mobile phone to raise the alarm.
Tony Blair, in his last day as prime minister, expressed sympathy for the families of the dead and said more money would need to be spent on flood prevention.
Residents have left their homes in the village of Catcliffe
"I think we should all send our condolences and sympathy to the families of those that have lost their lives," he told the House of Commons.
The Environment Agency still has several severe flood warnings in place, and forecasters are warning that flood-hit areas could be hit by more rain at the weekend.
The Environment Agency has advised people worried about flooding to call its Flood Line on 08459 881 188.