The unprecedented downpour over Cumbria was the highest level of rainfall measured in the country since records began, forecasters said today.
The record-breaking rainfall - reaching 314mm (12.4 inches) in 24 hours - is the highest level witnessed in 44 years.
The reading taken from the Environment Agency's gauging station at Seathwaite Farm exceeds the 279.4mm (11in) recorded in 24 hours in Martinstown, Dorset, in July 1955.
Statistics compiled by MeteoGroup, the weather division of the Press Association, show the deluge is the greatest seen since meteorologists started using instruments to record rainfall - back in 1727.
Forecasters described the devastating rainfall over Cumbria as at "historical" levels for the country.
Environment Agency chairman Lord Smith was in Cockermouth this morning.
He said: "This is an extremely serious incident - our thoughts are with those people whose homes have been flooded.
"We have seen unprecedented rainfall, with what we believe is a record amount for a 24-hour period in England." The Environment Agency Floodline service has received more than 12,000 calls from members of the public over the last 48 hours and issued more than 43,000 flood alerts via phone, text, email and fax.
Julian Mayes, a forecaster with MeteoGroup, said the levels of rain in Cumbria were equivalent to five or six months of rainfall typically experienced over London and the south east of England.
"The fact that there's eight feet of water in some places is not that surprising," he said.
"Primarily, it's the sheer quantity in the last 36 hours that has caused the flooding.
"But in November the ground is saturated. The rain can't get into the soil, it just runs off.
"That means rivers rise very quickly and suddenly."
Mr Mayes said the river levels across Cumbria should stabilise throughout the day.
Notable 24 hour rainfall totals in the UK, compiled by MeteoGroup UK:
* Seathwaite, Cumbria, November 19 2009 - 314mm*
* Martinstown, Dorset, July 18 1955 - 279.4mm
* Bruton (Sexey's School), Somerset, June 28 1917 - 242.8mm
* Upwey (Friar Waddon), Dorset, July 18 1955 - 241.3mm
* Cannington, Somerset, August 16 1924 - 238.8mm
* Loch Sloy Main Adit, Strathclyde, January 17 1974 - 238.4mm
* Long Barrow, Devon, August 15 1952 - 228.6mm
* Upwey (Higher Well), Dorset, July 18 1955 - 228.6mm
* Bruton (King's School), Somerset, June 28 1917 - 215.4mm
* Timberscombe, Somerset, June 28 1917 - 213.1mm
* Rhondda (Lluest Wen Reservoir), Glamorgan, November 11 1929 - 211.1mm
* Upwey (Elwell), Dorset, July 18 1955 - 211.1mm
* Kinlochquoich, Highland, October 11 1916 - 208.3mm
* Seathwaite, Cumbria, November 12 1897 - 204.0mm
* Camelford, Cornwall, July 8 1957 - 203.2mm
* Bruton (Pitcombe Vicarage), Somerset, June 28 1917 -200.7mm
* Wynford House, Dorset, July 18 1955 - 200.7mm
* Otterham, near Boscastle, August 16 2004 - 200.4mm
*Figure recorded by the Environment Agency