Flood zone D

Checked against FEMA and other official sources · Last reviewed October 8, 2026

What zone D means

Federal regulations define zone D in one line: "Area of undetermined but possible, flood hazards." FEMA's glossary says the same in plainer words: "Areas with possible but undetermined flood hazards. No flood hazard analysis has been conducted."

FloodSmart, the National Flood Insurance Program's (NFIP) official site, explains that because no analysis has been done "to determine probability, the flood risk in these areas is undetermined." It also says "'undetermined risk' doesn't mean 'no risk.'" It means the analysis has not been completed yet.

FEMA's fact sheet on zone D behind levees starts with a general description. It says that in some cases there are areas "with a potentially moderate to high risk of flooding, but the probability has not been determined," and these are labeled zone D. Compare that with flood zone A, where the high-risk area is mapped but the base flood elevation is not. [1][2][3][4]

Where zone D shows up

FEMA's map-reading guide says some flood maps "include areas where there are possible, but undetermined, flood hazards or unstudied areas." Those areas are shown as zone D. The NFIP's Flood Insurance Manual (April 2021) describes several situations:

• Unmapped parts of mapped communities. Zone D "designates flood hazard areas within mapped communities that remain undetermined and unmapped."
• Sparsely populated areas. The manual says the D zone reflects an area where the flood hazard is undetermined "and where there is sparse population."
• Land a community takes in. Agents may use zone D for rating when a community incorporates part of another community's area where no map has been prepared. They also use zone D if the map shows an area as unmapped.

Behind some levees. Since FEMA updated its levee analysis and mapping procedures in 2013, it has used zone D for some areas on the land side of levees that do not meet FEMA's accreditation standards. FEMA says such a levee "might provide some level of risk reduction," so zone D shows that "while flood risk remains, the probability of that flood risk has not been quantified." [3][5][6]

Is flood insurance required in zone D?

Not by federal law based on the zone alone. The regulation that lists the zones where "the mandatory purchase of insurance is required" covers the A and V zones, and zone D is not on it. The federal law behind that rule applies to buildings in areas FEMA has identified "as an area having special flood hazards."

Your lender can still ask for it. FEMA's fact sheet on zone D behind levees says that in zone D "there are no mandatory flood insurance requirements," but also that "some federally backed lenders may still require it." FloodSmart adds that "some banks require flood insurance even if you don't live in a high-risk area." Check your loan documents or ask your lender.

There's one more rule to know. If your property has received federal disaster assistance before, you must have flood insurance to qualify for future disaster assistance. FloodSmart says this requirement "is tied to a property, not an individual homeowner."

FloodSmart's advice for zone D is that "though not mandatory by law, insurance is strongly recommended." See do I need flood insurance?. [1][3][4][7][8]

Getting and pricing flood insurance in zone D

You can get NFIP flood insurance if your city or town participates in the NFIP's floodplain management requirements. FloodSmart says most communities in the U.S. participate. FEMA's fact sheet on zone D behind levees suggests you "contact your insurance agents to see what flood insurance policies are available for your property."

FEMA's glossary says zone D "flood insurance rates are commensurate with the uncertainty of the flood risk." FloodSmart says much the same: "Insurance rates are based on the uncertainty of the flood risk."

FEMA also says the NFIP's current pricing approach "does not use flood zones to determine flood risk." That approach applied to new policies from Oct. 1, 2021, and to all renewing policies from April 1, 2022. So your zone D label won't set your premium by itself. The glossary and FloodSmart pages don't explain how today's pricing treats zone D. Get a quote for your own building. See flood insurance cost. [2][3][4][8][9]

Building in zone D

FEMA's fact sheet on zone D behind levees says "there are no minimum building requirements by FEMA" in zone D. That doesn't mean your community has none:

• Federal rules say every NFIP community must "take into account flood, mudslide (i.e., mudflow) and flood-related erosion hazards, to the extent that they are known, in all official actions relating to land management and use."
• The NFIP's floodplain rules are "minimum standards." Any community may adopt stricter ones, and stricter state or local rules "are encouraged and shall take precedence."

For zone D areas behind levees, FEMA suggests communities "apply the same standards that are in place for the floodplain." It also says developers might be well served "to avoid significant development in Zone D, and/or to build to a higher elevation standard." For property owners, it suggests basic floodproofing steps, "such as elevating utilities and taking other special measures in basements."

Rules vary by community. Ask your local floodplain manager what applies to your lot before you build. [3][10]

Checking your map

FEMA's Flood Map Service Center (msc.fema.gov) is "the official public source for flood hazard information produced in support of the NFIP." You can also get the date of your current map from your local community official. See what flood zone am I in?.

Maps change. FloodSmart says FEMA and the NFIP "update the flood maps periodically" and suggests you "check annually." For lower-risk mapped areas, see flood zone X. For the full list of zone codes, see FEMA flood zones explained. [4][6]

Questions people ask