Police have declared a 'major incident' in east Berkshire as the Environment Agency issues 14 severe flood warnings
Flooded homes along the River Thames are being evacuated and thousands more are at risk, with water levels expected to rise further over the next 24 hours.
Residents in one Berkshire village say the scenes are from a "horror movie".
Fourteen severe flood warnings are in place in Berkshire and Surrey, while two remain in Somerset.
PM David Cameron - who is in flood-hit Dorset - said it was not the time to change personnel amid criticism of Environment Agency head Lord Smith.
Communities Secretary Eric Pickles is answering an urgent question put by Labour in the Commons on the flooding crisis.
Homes in the Berkshire village of Datchet are underwater and thousands more along the lower River Thames, as far as Shepperton, are under threat.
Several Thames gauges are showing their highest levels since being installed in the 1980s and 90s.
Fire crews, who have been rescuing people from their homes in Staines, say they have never known waters so deep or a flood rescue operation on this scale.
In Windsor, Councillor Colin Rayner pleaded for the police and Army for help.
"We've got 50 volunteers here, we've got the vulnerable people out of their homes, now we need to get everyone else out," he said
Nearby, in the Berkshire village of Colnbrook, resident Asif Khan said his whole street was under water, his house was flooded and his fridge "just went bang".
"It's something out of a horror movie," he said, adding that he was now about to try to evacuate with his two small children.
Hurst village resident Paul Palmer said sewers there were blocked and they have been unable to use the toilet since Friday.
"It's starting to back up into the toilet - it's like going back to the dark ages," he told the BBC.
Stranded residents in Staines-upon-Thames are rescued by fire crews
A total of 10,000 sandbags have been distributed in Datchet in Berkshire
Swans wander down a flooded street in Worcester
Speaking from Portland, off the Dorset coast, Mr Cameron said: "I am only interested in one thing and that is making sure that everything government can do is being done and will go on being done to help people through this difficult time.
"There will be time later on to talk about things. Right now everybody's got to focus on the job in hand."
Mr Cameron's comments follow a deepening political row.
Speaking earlier, Lord Smith said his staff knew "100 times" more about flooding than any politician and pointed out that they were bound by rules laid down by government.
He has insisted again he will not resign.
Communities Secretary Eric Pickles previously said ministers had been given bad advice by the Environment Agency over river dredging.
Meanwhile, Environment Secretary Owen Paterson and Mr Pickles are thought to be at odds over the performance of the Environment Agency.
No 10 did not deny Mr Paterson had complained about his colleague, who is standing in for him after he had an eye operation, but said both were doing an "excellent job".
Earlier, Deputy Prime Minister Nick Clegg, who was in Burrowbridge in Somerset, said dredging should have been done over the last few years but added: "I don't think now is the time to point the finger of blame."
Among other developments:
- Environment Agency has issued 14 severe warnings - meaning "danger to life" - along the River Thames, in areas including Staines, Chertsey and Datchet
- Two severe warnings are in place for the south-west of England in Salt Moor and East Lyng, in Somerset
- Large parts of Worcester city centre could be closed for a weekbecause of flooding, the county council has said. Twenty-nine flood warnings remain in place across Herefordshire and Worcestershire
- An earth bank has been built to protect the town of Bridgwater, on the edge of the Somerset Levels, from flooding
- Dyfed Powys police have found a body in their search for a kayaker who went missing on the River Usk on Sunday
- A meeting of the emergency Cobra committee will take place later. Mr Cameron will take part by phone from the South West.
- Essex County Council says it is releasing £1m of emergency funds to tackle road flooding across the county
Thames Valley Police have declared a "major incident" in east Berkshire.
Howard Davidson, from the Environment Agency said he expects conditions in Berkshire to deteriorate as more rain falls over the coming days.
"We have issued flood warnings from Datchet down to Shepperton, and we urge people to take heed of the flood warnings. We are anticipating another three or four inches on the Thames over the next 24 hours."
Severe delays
The flooding has also caused severe delays on several train lines, National Rail said.
Robin Gisby, managing director of Network Rail, said his team were watching "several hundred" sites across England carefully.
"What I think is really significant, and it has got worse overnight, is Oxford down to the Thames Valley through Didcot, Reading, Maidenhead and into Paddington.
"This isn't now just flooding, this is groundwater. The land is so saturated we have got water rising up, just as much as flowing on to it. So it is difficult."
The main rail route into Devon and Cornwall via Bridgwater remains cut off because of problems caused by flooding and storm damage.
The line from Paddington to Exeter via Newbury is expected to reopen later following a drop in flood water levels at Athelney.
The line from Waterloo to Exeter via Yeovil, closed due to a landslip at Crewkerne on Saturday, has reopened.
More than 300 less serious warnings and alerts have been issued by the Environment Agency, mostly in southern England and the Midlands.
The Met Office has no rain warnings in place for Monday, but it is warning of ice across much of the UK.
But forecasters say another area of low pressure is expected to reach the UK on Monday night and into Tuesday, bringing more heavy rain.
Peter Sloss, of the BBC Weather Centre, said Monday would be the "driest day of the week" but he warned there would be 20-40mm (1-2in) of rain for many areas by the end of Thursday.
He said some showers would be wintry, with snow likely on higher ground in Wales, Scotland, Northern Ireland and northern England.
Some residents in Staines, which borders the River Thames, were woken by telephone flood alerts
In Burrowbridge, Somerset, sandbags are stacked up ready for use
Deputy Prime Minister Nick Clegg fields questions from reporters nearby in Burrowbridge
Rail services have been cancelled in parts of Surrey and Berkshire
