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NYC Flood Map  ·  Bronx

Bronx Flood Map

Stormwater is the most widespread flood exposure in the Bronx: 39% of its 89,253 lots rate Moderate or High. Next is sewer backup, at 19%. Below, what drives each kind of flooding here, from city and federal sources and Flood Form's parcel data.

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Belmont (HP-004): 39% Moderate or High for stormwaterClason Point (HP-011): 41% Moderate or High for stormwaterConcourse (WI-064): 43% Moderate or High for stormwaterConcourse Village (WI-075): 39% Moderate or High for stormwaterCrotona Park East (HP-003): 36% Moderate or High for stormwaterEastchester (HP-023): 51% Moderate or High for stormwaterEdenwald (HP-031): 7% Moderate or High for stormwaterFordham (WI-057): 29% Moderate or High for stormwaterHighbridge (WI-061): 48% Moderate or High for stormwaterHunts Point (HP-002): 42% Moderate or High for stormwaterLongwood (HP-025): 37% Moderate or High for stormwaterMelrose (WI-072): 37% Moderate or High for stormwaterMorris Heights (WI-058): 20% Moderate or High for stormwaterMorris Heights (WI-059): 37% Moderate or High for stormwaterMott Haven (WI-066): 56% Moderate or High for stormwaterMott Haven (WI-067): 23% Moderate or High for stormwaterMott Haven (WI-068): 34% Moderate or High for stormwaterMount Eden (WI-062): 44% Moderate or High for stormwaterPelham Bay (HP-015): 42% Moderate or High for stormwaterPort Morris (WI-070): 52% Moderate or High for stormwaterPort Morris (WI-071): 45% Moderate or High for stormwaterRiverdale (WI-053): 35% Moderate or High for stormwaterRiverdale (WI-054): 22% Moderate or High for stormwaterRiverdale (WI-056): 35% Moderate or High for stormwaterSchuylerville (HP-016): 50% Moderate or High for stormwaterSchuylerville (HP-017): 44% Moderate or High for stormwaterSchuylerville (HP-018): 45% Moderate or High for stormwaterSchuylerville (HP-019): 35% Moderate or High for stormwaterSchuylerville (HP-020): 40% Moderate or High for stormwaterSchuylerville (HP-026): 48% Moderate or High for stormwaterSoundview (HP-008): 49% Moderate or High for stormwaterSoundview (HP-009): 50% Moderate or High for stormwaterSpuyten Duyvil (WI-076): 35% Moderate or High for stormwaterSpuyten Duyvil (WI-077): 60% Moderate or High for stormwaterThrogs Neck (HP-021): 30% Moderate or High for stormwaterThrogs Neck (HP-022): 46% Moderate or High for stormwaterUnionport (HP-012): 18% Moderate or High for stormwaterUnionport (HP-013): 33% Moderate or High for stormwaterWakefield (HP-024): 41% Moderate or High for stormwaterWestchester Square (HP-033): 53% Moderate or High for stormwaterWilliamsbridge (HP-014): 33% Moderate or High for stormwaterWoodlawn (HP-007): 42% Moderate or High for stormwater
Stormwater, Moderate or High0–15%15–30%30–45%45–60%60%+

Shaded areas are the combined-sewer sewersheds with their own page; select one to open it. Unshaded parts of the Bronx still get a lot-by-lot rating in every Flood Form report.

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Flood exposure across the Bronx

The share of 89,253 lots Flood Form rates Moderate or High for each type of flooding, on the same Minimal to High scale as an individual report.

39%

Stormwater exposure: Moderate or High

19%

Sewer Backup exposure: Moderate or High

4%

Groundwater exposure: Moderate or High

4%

Coastal exposure: Moderate or High

3.9%

Lots in FEMA's 1% annual-chance floodplain

2.8%

Lots inside the 2012 Hurricane Sandy flood area

97%

Lots draining to a combined-sewer outfall

1.5%

Lots with a DEP-confirmed sewer backup on record

Computed from Flood Form’s NYC parcel data as of October 19, 2026

Why the Bronx floods

Stormwater

In Flood Form's data, 39% of lots in the Bronx rate Moderate or High for stormwater.

Ida damaged about 6% of all Bronx buildings, double the rate of other boroughs, with the worst east of the Bronx River: about 9% in Co-op City and Throgs Neck.[1]

City sewers are built to drain roughly 1.75 inches of rain an hour, and some older ones less: before 1977 each borough set its own standard.[2]

Hurricane Ida brought 3.15 inches in a single hour to Central Park in 2021. More than half of the damage it caused fell outside both FEMA floodplains and the City's own stormwater flood scenarios.[2][1]

Flooding doesn't always follow the heaviest rain: in the September 2023 storm, parts of southern Queens and coastal Staten Island flooded badly with little intense rainfall, which the Comptroller tied to gaps in drainage.[3]

Sewer backup

In Flood Form's data, 19% of lots in the Bronx rate Moderate or High for sewer backup, and 97% drain to a combined-sewer outfall.

DEP names the Bronx among the boroughs where older combined sewers fall short of today's design standard.[4]

About 60% of the city's sewer system is combined, carrying both sewage and stormwater in one pipe. When intense rain exceeds pipe capacity, that mix can back up through basement drains and fixtures.[4]

DEP reports that rain-driven backups are now the most common kind, overtaking backups from grease and wipes, and that about 74,000 properties, most of them one- and two-family homes, are vulnerable in a storm of 1.75 inches per hour.[4]

Homes whose drains and fixtures sit below the nearby sewer, such as basements reached by a downward-sloping driveway, are the most likely to back up.[4]

Groundwater

In Flood Form's data, 4% of lots in the Bronx rate Moderate or High for groundwater, and 13% sit near a buried historic stream or pond.

The City's hazard mitigation plan names groundwater flooding a particular concern where neighborhoods were built while pumping held the water table down, and notes parts of Brooklyn and Queens where groundwater sits less than 10 feet below the surface. It adds that research on the problem is at an early stage.[5]

Coastal flooding

In Flood Form's data, 4% of lots in the Bronx rate Moderate or High for coastal flooding. 3.9% fall in FEMA's 1% annual-chance floodplain, and 2.8% were inside the area Hurricane Sandy flooded in 2012.

The Bronx and Hutchinson Rivers can flood, and the City's plan notes concentrated flood insurance claims in the low-lying southeast Bronx.[5]

Coastal flooding comes mainly from storm surge, while tidal flooding can happen on ordinary high tides without a storm.[5]

FEMA flood maps show coastal and river flooding, not the rainfall and sewer flooding behind most basement deaths in Ida.[6]

Neighborhoods in the Bronx with the most stormwater exposure

Combined-sewer sewersheds in the Bronx, ranked by the share of lots rated Moderate or High for stormwater.

All 42 Bronx sewersheds

Questions about flooding in the Bronx

Is the Bronx in a flood zone?

3.9% of lots in the Bronx fall in FEMA's 1% annual-chance floodplain, the "flood zone" on federal maps, and 2.8% were inside the area Hurricane Sandy flooded. Federal maps cover coastal and river flooding, not rainfall: in Hurricane Ida, more than half of all damage fell outside FEMA floodplains and the City's stormwater scenarios. In Flood Form's data, 39% of lots here rate Moderate or High for stormwater.

Why does the Bronx flood?

The most widespread exposure in the Bronx is stormwater, with 39% of lots rated Moderate or High, followed by sewer backup at 19%. The remaining shares: groundwater 4%, coastal flooding 4%. Flash flooding happens when rain falls faster than the local sewers can drain it, and DEP reports that rain-driven backups are now the most common kind of sewer backup.

Which the Bronx neighborhoods flood the most?

In Flood Form's data, the sewersheds in the Bronx with the largest share of lots rated Moderate or High for stormwater are Spuyten Duyvil (WI-077), Mott Haven (WI-066) and Westchester Square (HP-033). That ranking covers only the combined-sewer areas with their own page; every lot elsewhere is still rated in its own Flood Form report.

How can I check flooding at my the Bronx address?

Enter your address for a free Flood Form. It rates the lot for stormwater, sewer backup, groundwater, and coastal flooding on a Minimal to High scale and recommends measures suited to it.

Sources

  1. [1] NYC Emergency Management, Record Rain in NYC: The Impacts of Post-Tropical Cyclone Ida (Damage Analysis Report) (2024).
  2. [2] NYC Department of Environmental Protection, Increasing Stormwater Resilience in the Face of Climate Change: Our Long Term Vision (2022).
  3. [3] NYC Comptroller, Is New York City Ready for Rain? An Investigation into the City's Flash Flood Preparedness (April 2024).
  4. [4] NYC Department of Environmental Protection, Protecting Your Home: Tools to Prevent Basement Sewer Backups and an Evaluation of Backwater Valves (December 2024).
  5. [5] NYC Emergency Management, NYC Hazard Mitigation Plan: Flooding Hazard Profile (current edition).
  6. [6] Scientific American, Deaths from Hurricane Ida Expose Flaws in FEMA Flood Maps (September 2021).

Bold sentences come from Flood Form’s parcel data and describe exposure across the borough, not the conditions at any one property. A Flood Form report rates an individual lot.

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