A "one hundred year flood" is not defined as "a great flood, the probability of which will only happen once every century" (or something like that). A "one hundred year flood plain" is an area, as mapped by the federal government, in which there is approximately a 1% chance of flooding every year.
This means that, over the 30-year life of a mortgage, there is actually a 24% chance of flooding. Very generally speaking, the same home has a 9% chance of fire damage over the same period, yet who doesn't buy fire insurance? Something about people's visceral fear of fire, and abstract fear of some "100 year flood," to be sure.
The reason I go into this explanation is because words are powerful (I guess I did learn something from my time in politics) and I believe that this misleading terminology is part of the reason that so few people carry flood insurance (there were only 74 residential flood policies in place in the City of Binghamton, in a city of 45,000 people).
Like fire insurance, flood damage is not covered under general homeowner's insurance and must be purchased separately. It is easy to see why so many (already pretty low income) poeple would skip buying a policy for something that is only supposed to happen every 100 years.
I want people to know that these are not a bunch of dumb hicks who should have known they needed flood insurance. With all the buzz about global warming, I have a feeling it's going to be a bumper-crop year for flood insurance, both here and around the nation. Hey, there must be some money to be made in that observation . . .