Images last week of North Dakota residents working feverishly in below-freezing weather to sandbag the banks of the Red River and save their towns have been compelling. And it should also make one think, how safe is my home from flooding? Although flooding is considered a disaster that affects houses built in river basins, the truth is virtually no home is flood-proof. If your house is built on flat ground, it doesn't matter how close you may be to a body of water -- a rapid snowmelt, a terrific storm or even an area drainage problem could put you under water. And if your home is up on a hill, don't get too comfortable. Water running down can be diverted accidentally and get your sneakers wet in the living room. Unfortunately, when people see the threat of flooding, they assume their homeowner's policy will be enough to cover the damage. But flooding is the most common natural disaster in the U.S., and consequently most policies exclude flood damage. In 1968, the National Flood Insurance Program (NFIP) was formed to cover devastating water disasters and policies were sold through private insurers. Some of the biggest insurers include Allstate ( ALL) and Geico, owned by billionaire investor Warren Buffett's Berkshire Hathaway ( BRK.A). So are you at risk for flood damage? An easy way to check is to look up Floodsmart.gov, a Web site run by the NFIP. You can enter your address and the database will let you know whether your property is in a low-, medium- or high-flooding risk area and how much you could expect to pay for flood insurance. Low-risk area residents shouldn't get too comfortable, though. The NFIP estimates that 25% of its annual claims come from low- and medium-risk areas.