Is Delaware County, PA in a flood zone?
FEMA's National Risk Index puts Delaware County's flood hazard at the 94.4th percentile nationally — well above the national norm for flood hazard — driven by inland rivers and flash flooding rather than the coast — FEMA's model puts a flood event here at about 4.6 times a year. That's a county-wide figure, not a per-address one — FEMA's parcel maps are a live lookup, not a bulk file.
Delaware County's flood-insurance compliance gap
38.6% of the homes FEMA requires to carry flood insurance in Delaware County — those inside the mapped Special Flood Hazard Area — actually have a policy in force: 700 policies against 1,813 mandated structures, which means a meaningful share of legally-required coverage simply isn't there. Across all residential structures in Delaware County, not just the ones FEMA mandates, 0.7% carry an NFIP policy — most flood damage nationally happens outside the mapped high-risk zone, so that broader number matters too.
How Delaware County compares nationally
Delaware County sits at rank 190 of 3144 counties on FEMA's flood hazard scale (1 is worst) and rank 122 of 3144 by population (1 is biggest). About 584,882 people live in Delaware County, Pennsylvania, spread over 183.808 square miles.
What to do next if you own or are buying in Delaware County
Across all of Delaware County's 170,879 residential structures, 1,153 carry an NFIP policy today — a county-wide count that still can't tell you one address's own mapped zone.
More on how this number was built
The methodology guide shows exactly which FEMA and Census tables feed Delaware County's numbers. The guide to what the Special Flood Hazard Area actually means explains why the mandatory-insurance rule exists and who it applies to.