Sewershed OH-005 · NYC DEP Combined Sewer Overflow Tributary Area
OH-005 - Gowanus, Brooklyn
Properties in this area share the OH-005 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 Gowanus, Brooklyn specifically.
OH-005 is a combined sewer area covering 336 properties in Gowanus, Brooklyn. Flood Form rates 79% of them Moderate or High for stormwater exposure, and 75% for groundwater. 48% of lots have yard area that legally qualifies for on-site infiltration. Ground elevation is typically 19 ft. The median building dates to 1931. 69% of parcels sit over a historic stream or pond.
336
Properties in sewershed
47.6%
Legally eligible for on-site infiltration
79%
Stormwater exposure: Moderate or High
75%
Groundwater exposure: Moderate or High
What sets OH-005 apart
19 ft
Median ground elevation
90%
Average impervious cover per lot
1931
Median year built
69%
Properties over a historic stream or pond
Stats computed from Flood Form’s NYC parcel data as of October 9, 2026
Common solutions for Gowanus 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
- RH-034Prospect Heights4,975 properties · 38% with Moderate or High stormwater exposure
- RH-035Carroll Gardens815 properties · 23% 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-006Park Slope3,208 properties · 27% with Moderate or High stormwater exposure
- RH-016Cobble Hill2,042 properties · 18% with Moderate or High stormwater exposure
Want to see where your specific property stands?
Get Your Property’s Flood Form