The highest ever number of properties vulnerable to flooding are now registered on the Environment Agency's free flood warning service, it has been revealed.
But homeowners and businesses were warned that those susceptible to flooding should still check if their property is at risk of river or coastal flooding and sign up for free warnings.
One sixth of properties in England has a high flood risk, the agency said.
The agency's report found that four times the number of homeowners and businesses had signed up to its national flood warning service since 2005.
There were 300,000 subscriptions in 2008, compared with the 1.1 million people now signed up.
About 60% of properties with a high flood risk are now signed up to the system, up from the 14% signed up in 2008.
The number of areas eligible to sign up to the free service is being continually expanded, the agency said.
Homes that are in high risk flood areas would benefit from home insurance, in case of water damage to their property.
Chief executive of the Environment Agency, Dr Paul Leinster, said home and business owners should consult the Environment Agency's website to see if their house is at risk of flooding and for advice on the "simple steps they can take to prepare for flooding such as signing up for free river and sea flood warnings."
© Press Association 2011