Areas designated as Zones B and X or Zones C and X are classified as moderate- to low-risk zones. For houses in these areas, flood insurance is an option, but not required. B zones are usually protected by levees, dams or dikes. Zone C residents might be located near a pond, or in an area with local drainage problem, but they still have a moderate to low risk of flooding.
Those living in the high-risk areas -- Zones A, AE, A1-30, AH AO, AR and A99 -- must have flood insurance. Zone A has a 1 percent annual chance of flooding and a 26 percent chance of flooding over a 30-year period. In some of these zones, base flood elevation is known; in others, it is not. People in Zone AO live near a river, a stream or a lake. Zone AR houses are near a levee, dam or dike that is being reconstructed.
High-risk coastal areas include Zones V, VE and V1-30. These areas have a 1 percent chance of flooding annually. Over a 30-year span, the chance of flooding is 26 percent. These locations are also at risk of storm waves causing damage.
Zone D is an undetermined area. The flood risk in these areas has not been determined yet. No analysis of flood hazard has been done.
