The Environment Agency cannot protect all people and all properties but will do all it can, the executive director says.
Around half of services to London out of Brighton have been cancelled because of major flooding at Patcham, near Preston Park.
Insurers are to make around £426 million worth of payouts for the destruction caused by severe flooding over Christmas and New Year.
David Cameron has unveiled a £10 million package of support for businesses hit by the floods.
Small and medium sized businesses will be able to access the funds to help with clean up costs and to keep trading throughout.
A helpline will also open to give advice, as well as 'no penalty charges' for those who are late filing accounts because of the crisis.
The Prime Minister has said:
– David Cameron, Prime Minister
The Government is taking action across the board to deal with the clear-up
and help hard-working people affected by the floods.
Dealing with these floods will be a long haul, requiring a stepped-up
national effort with the whole country pulling together.
We will continue to help the people who need help and protect the
communities that need protecting."
The Environment Agency (EA) said 16 severe flood warnings remain in place for the South West and the Thames Valley, with almost 130 flood warnings and more than 180 flood alerts.
Mr Cameron has been monitoring efforts to control the flooding in Oxfordshire where his constituency is, in Witney.
– David Cameron, Prime Minister
The recent flooding has been a tragedy for all those affected and my thoughts are with them. While it is of no comfort to those individuals, over 1.3 million other homes have been protected since December and we will continue to invest in flood defence measures to protect even more.
He said tonight: "I am hopeful that the work to strengthen long-term flood defences, and the emergency measures which have been put in place over recent days and weeks will mean that we can minimise the number of homes and businesses affected by the latest high water levels.
No trains ran on Sunday between Leamington Spa and Banbury due to a landslip. Chiltern Railways advised customers north of Banbury to use Virgin Trains between London Euston and Birmingham New Street.
Chiltern Trains plan to run a normal timetable on Monday, 17 February but will need to pass the area at a reduced speed.
FGW is planning to run a near normal service on high speed routes into and out of London on Monday with the exception of the route closures at Dawlish, and between Bridgwater and Taunton. Buses will run on those routes that are closed.
Local services will also be running between Reading and London on Monday, although because of the flooding affecting signalling equipment near Maidenhead, there will be a small number of trains that we won't be able to run.
Mark Hopwood, First Great Western managing director, said:
– Mark Hopwood, First Great Western
This is great news for our passengers, who have faced a very difficult period of travel. We are finalising a new amended timetable, which we will publish through our online systems later today. To help customers who postponed journeys last week, ticket restrictions remain lifted until Monday. Customers are strongly advised to check our website before setting off in the morning."
First Great Western (FGW) and Network Rail plan to restore the majority of services into and out of London Paddington from Monday.
Network Rail's engineering and maintenance teams have been working to try and solve the problems caused by the flooding at Maidenhead that had affected the normal signalling system reducing service to just 20% of normal capacity.
Through a series of innovative engineering solutions, from start of service on Monday, in excess of 75% of normal services will be running.
The Prime Minister chaired another meeting of the Government's Cobra emergency committee this evening as the huge clean-up operation was getting underway.
But many areas of flood-hit Britain must prepare for water levels to rise once again as further rain is forecast over the coming days, bringing further misery to residents whose homes have already been flooded.
Swathes of the UK remain on high alert as people battle to protect their homes and communities from the floodwaters, which are still expected to rise in places despite today's calmer conditions.