FEMA Flood Maps Omit Millions of High-Risk Homes, Report Says

A new study finds that many homeowners face a higher flood risk than they expect. It’s a prospect that raises questions about the accuracy of government flood maps that determine insurance coverage, costs, and building sites.

The Neptune Flood Research Group says that the Federal Emergency Management Agency’s (FEMA) flood maps, long considered the gold standard, might not be accurate after all. Instead, the group asserts that these maps may be significantly off from the number of houses actually at risk. The group is the research arm of Neptune Flood Insurance, a private flood insurance company that sells primary and excess flood insurance.

Millions of additional at-risk homes

Almost 10 million houses at risk of flooding aren’t in FEMA-designated flood zones, according to the Neptune Group’s research. This means affected homeowners might pay less for insurance but may not have sufficient coverage or fully understand the risks they face in their area.

The Neptune Group report says FEMA’s maps have always been a key source of information on flood risk, helping determine where to build, how to insure assets, and how to prepare for floods. But outdated, insufficient maps leave millions of homeowners unprepared for flooding.

The report also states that FEMA continues to use maps from the ’70s and ’80s for most of the country and updates them only every seven years.

Floods outside ‘high-risk’ flood zones

In the last 10 years, almost 30% of National Flood Insurance Program (NFIP) claims were for properties in areas FEMA says aren’t high-risk. This has been especially true in areas with rapidly growing cities, where the number of houses at risk could be five to eight times FEMA’s estimate.

From 2019 to 2023, developers built over 211,000 houses in areas that could flood severely but don’t appear on FEMA’s maps, the report says. Because FEMA classifies those areas as low-risk, builders and homeowners often don’t face strict building codes or flood insurance requirements.

And flood threats exist in more than just coastal areas. More rain, flash floods, inland storms, warmer oceans, and rising sea levels are all increasing flood risk faster than FEMA can update its maps.

What’s next? Calls for change

The researchers recommend FEMA update and expand its flood maps to reflect current conditions. They also recommend FEMA update the maps more frequently, cover more areas where cities are growing, and use data that reflects different types of flooding, such as from rainfall and climate change, not just from storms and rivers.

The report also suggests FEMA could adopt flood-risk systems used by private insurers. Such systems test numerous flood scenarios using highly detailed data and weather predictions. Doing so could make the maps more accurate and reduce the time and cost to create them.