One of the UK's largest insurers has unveiled technology that will enable it to pinpoint whether individual homes are at risk from flood.
At present insurers assess risk through checking if the postcode of the property is in a flood plain.
Nearly five million people live in a flood plain, which makes it hard for them to get cover.
Norwich Union has digitally mapped the UK and can now calculate the risk of flood to within a few metres.
The insurer will be able to set premiums for home contents insurance based on a particular address, rather than just a postcode band, for both residential and commercial properties.
As well as showing whether an individual property is at risk, the map shows how often a flood is likely to occur and to what depth.
The multi-million pound project is launching for new customers in parts of Shropshire and Norfolk on Wednesday.
Norwich Union customers in the two counties - which are seen as high flood-risk areas - will have their properties assessed for flood risk at their renewal date.
In October 2000, flooding in Shropshire cost the insurance industry a total of £1bn, with the claims bill for Norwich Union topping £200m.
The mapping project will be completed by the end of 2004.
The insurer estimates that the map could mean that across the UK up to 600,000 properties previously deemed too risky to insure could now get cover.
"Because of the level of detail provided by the map, people who previously thought their property was uninsurable could now obtain cover," said Laurence Loughnane, head of underwriting at Norwich Union.
"The ability to pinpoint whether an individual house is on a hill or raised ground, and how floodwaters will flow, is invaluable in the fight against flood damage," he added.