Sewershed OH-004 · NYC DEP Combined Sewer Overflow Tributary Area
OH-004 - Sunset Park, Brooklyn
Properties in this area share the OH-004 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 Sunset Park, Brooklyn specifically.
OH-004 is a combined sewer area covering 4,117 properties in Sunset Park, Brooklyn. Flood Form rates 21% of them Moderate or High for stormwater exposure, and 26% for groundwater. 77% of lots have yard area that legally qualifies for on-site infiltration. Ground elevation is typically 69 ft. The median building dates to 1915. 33% of parcels sit over a historic stream or pond. According to NYC DEP green infrastructure records, this sewershed drains to East River / Open Waters. NYC DEP has built 6 green infrastructure assets here.
4,117
Properties in sewershed
76.5%
Legally eligible for on-site infiltration
21%
Stormwater exposure: Moderate or High
26%
Groundwater exposure: Moderate or High
What sets OH-004 apart
69 ft
Median ground elevation
83%
Average impervious cover per lot
1915
Median year built
33%
Properties over a historic stream or pond
Stats computed from Flood Form’s NYC parcel data as of October 9, 2026
Common solutions for Sunset Park 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
- OH-006Park Slope3,208 properties · 27% with Moderate or High stormwater exposure
- RH-030Carroll Gardens482 properties · 40% with Moderate or High stormwater exposure
- OH-003Sunset Park3,000 properties · 19% with Moderate or High stormwater exposure
- OH-007Park Slope3,227 properties · 22% with Moderate or High stormwater exposure
- RH-031Carroll Gardens324 properties · 35% with Moderate or High stormwater exposure
- OH-005Gowanus336 properties · 79% with Moderate or High stormwater exposure
Want to see where your specific property stands?
Get Your Property’s Flood Form