Sewershed HP-013 · NYC DEP Combined Sewer Overflow Tributary Area
HP-013 - Unionport, Bronx
Properties in this area share the HP-013 combined sewer — during moderate-to-heavy rain, runoff can exceed pipe capacity faster than it drains, which is what drives sewer backup exposure block by block. Here’s what that looks like for Unionport, Bronx specifically.
HP-013 is a combined sewer area covering 4,602 properties in Unionport, Bronx. Flood Form rates 33% of them Moderate or High for stormwater exposure, and 14% for groundwater. 87% of lots have yard area that legally qualifies for on-site infiltration. Ground elevation is typically 24 ft. The median building dates to 1945. 5% of parcels sit over a historic stream or pond.
4,602
Properties in sewershed
86.8%
Legally eligible for on-site infiltration
33%
Stormwater exposure: Moderate or High
14%
Groundwater exposure: Moderate or High
What sets HP-013 apart
24 ft
Median ground elevation
82%
Average impervious cover per lot
1945
Median year built
5%
Properties over a historic stream or pond
Stats computed from Flood Form’s NYC parcel data as of October 9, 2026
Common solutions for Unionport properties
Downspout Diversion
Redirects roof runoff away from the combined sewer and into landscaped or permeable areas on the lot.
Infiltration System
Drywells or infiltration chambers that let stormwater soak into the ground on-site instead of entering the sewer.
Detention System
Holds stormwater temporarily and releases it slowly, reducing peak flow into the combined sewer during a storm.
Drain Improvement
Upgrades yard, area, or foundation drains so water is carried away from the building instead of pooling.
Foundation Waterproofing
Protects the foundation from groundwater intrusion, relevant where groundwater exposure runs high.
Nearby sewersheds
- HP-012Unionport745 properties · 18% with Moderate or High stormwater exposure
- HP-009Soundview1,644 properties · 50% with Moderate or High stormwater exposure
- HP-011Clason Point1,923 properties · 41% with Moderate or High stormwater exposure
- HP-033Westchester Square3,450 properties · 52% with Moderate or High stormwater exposure
- HP-008Soundview1,033 properties · 47% with Moderate or High stormwater exposure
- HP-016Schuylerville1,359 properties · 50% with Moderate or High stormwater exposure
Want to see where your specific property stands?
Get Your Property’s Flood Form