An MP has warned that errors in flood risk maps may increase insurance costs and reduce property prices.
David Davis, the Conservative MP for Haltemprice and Howden in East Yorkshire, issued the warning after the maps went online this month.
Mr Davis said he had been contacted by one constituent whose home was shown as a risk even thought it has not been flooded for 60 years.
The MP has asked the Environment Secretary to act quickly.
The maps were made available on the Environment Agency's website less than two weeks ago.
They were intended to allow householders to check flood risks more accurately than before by using postcodes to identify property locations.
However, within days Mr Davis, who is also shadow Home Secretary, said he had been approached by constituents claiming that the maps incorrectly indicated that their homes were flood risks.
In one particular case, he said, a couple found that a potential buyer for their house was put off at the last moment after seeing that the property was marked as being in a danger area, despite not having flooded since at least the 1950s.
"The Environment Agency claimed that the new flood maps would end the confusion surrounding flood risk," said Mr Davis.
"Clearly this is not the case. If a property that has not flooded in living memory is marked as at risk of flooding, then the maps lack the required precision."
"Insurance premiums may rise and property prices may fall for many of my constituents as a result."
The Environment Agency website does include a disclaimer stating that the maps are not wholly reliable in describing the risk to individual properties.
The Environment Agency was not available for comment.