Scientists have told Sky News that groundwater levels are now so high that parts of Britain face a serious risk of flooding for weeks or even months to come.
Andy McKenzie, a groundwater scientist at the British Geological Survey, told Sky News that even if the rain stopped today, so much water is soaking through the soil that levels are likely to keep rising for another two months.
The risk of flooding could remain high until May, he said.
Figures exclusively revealed to Sky News show that boreholes used to measure the height of the water table are overflowing in many areas, with the highest levels ever recorded.
According to the data from the British Geological Survey nine of the 14 boreholes in southern England are now showing "exceptionally high levels".
At Chilgrove House in Sussex the groundwater level at the end of January beat records going back 179 years.
And at a borehole at The Well House Inn in Surrey the extraordinary rainfall has pushed up the water table by 20 metres in the last two weeks.
The British Geological Survey estimates 1.6 million properties in England and Wales are at risk of groundwater flooding.
They tend to be in low-lying areas where water is pushed up through rocks. They can be in normally dry areas, far from rivers and streams.
The Environment Agency (EA) has already issued groundwater flood alerts for parts of south London, Kent, Surrey, Berkshire, Wiltshire, Hampshire and Dorset.
The EA warns that cellars are likely to flood, and if groundwater seeps into sewers, there could be pollution. Roads could also be closed by rising water levels.
In the winter of 2000-01 groundwater flooding of the Patcham area of Brighton cost £800,000 and cut off the London to Brighton railway line.
Water flowing underground is also likely to mean the Somerset Levels will remain flooded well into the Spring.
Sky News descended through a pothole in the Mendip Hills to access a network of caves that stretches for several miles.
Huge volumes of water are cascading through the tunnels, heading for the low-lying areas.
Andy Sparrow of Caveclimb has been exploring the system for several decades. He said he has never seen it so wet for so long.
With more storms forecast this week, and no sign the jet stream is moving north to its normal position, large areas of Britain are at risk of further flooding.
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