Plug In Your Address to See Odds of Flooding

The official stats we use to determine whether our homes are at risk of flooding are woefully out of date and understate the actual danger in a big way, according to a new initiative to set the record straight. Across the US, millions more homes are at risk than government estimates suggest, says the First Street Foundation, a nonprofit made up of scientists, engineers, and academics. Coverage:

• Your address: The foundation has a new "Flood Factor" tool that allows people to plug in their home address and see the newly calculated risk. Use it yourself here. Data will eventually be integrated at Realtor.com, notes Axios.

• Big picture: Flood maps from the federal government estimate that 8.7 million homes in the US are at risk, but the new research puts the figure at 14.6 million, reports the New York Times. Among other things, the foundation accounts for smaller creeks not on the federal maps, along with broader factors such as sea-level rise and rainfall. Its maps are also better able to calculate risk from intense rainfall, not just annual figures.
• One city's example: Chicago has the biggest gap among all cities, reports USA Today. Of the city's 600,000 properties, the Federal Emergency Management Agency says 0.3% are at risk, but the new database pegs it at 13%. That translates to about 75,000 additional properties at risk in the city.
• A definition: So what does "at risk" mean? It's used to designate homes with a 1% risk of flooding annually, which USA Today notes is the benchmark for purchasing flood insurance. But that percentage might be misleading: It translates into a 1-in-4 chance of flooding over the course of a 30-year mortgage.
• FEMA on board: First Foundation's Matthew Eby says "there are millions of Americans who have substantial flood risk and have no idea, and now they'll be able to access that," per Axios. FEMA is fine with this, welcoming the new information as a "complement" to its own. "We know there is no perfect science to predict flooding," says a spokeswoman, per the Times. "The Flood Factor product may help property owners with the critical decisions they must make and purchase necessary insurance."

(More flooding stories.)