Flood Zone X is an area designated by the Federal Emergency Management Agency as having a moderate or minimal risk of flooding, explains FEMA. On the Flood Insurance Rate Map, Zone X shaded refers to an area with moderate flooding risk, while Zone X unshaded refers to an area with minimal flooding risk.
Flood zones are a way to define the flooding risk for different areas, according to FEMA. All flood hazard areas are defined as part of a Special Flood Hazard Area, or SFHA. This area is considered to be a section of land fully covered by a flood that has a 1 percent chance of occurring in any given year or a flood more significant than that chance. Statistically, this area is certain to be flooded in a 100-year period. The flood statistically certain to occur within any 100 years is referred to as the 100-year flood or the base flood.
Zones outside the SFHA have a lower likelihood of flooding and these include Zones B, C and X, shaded and unshaded, states FEMA. Zones B and X shaded are areas at moderate risk of flooding that lie between the base flood area and the area of the flood five times less likely to occur than the base flood. Zones C and X unshaded are areas at minimal risk of flooding that are higher, and therefore less likely to be flooded, than areas of the flood five times less likely to occur than the base flood.