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Flood Form

Sewershed RH-016  ·  NYC DEP Combined Sewer Overflow Tributary Area

RH-016 - Cobble Hill, Brooklyn

Properties in this area share the RH-016 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 Cobble Hill, Brooklyn specifically.

RH-016 is a combined sewer area covering 2,042 properties in Cobble Hill, Brooklyn. Flood Form rates 18% of them Moderate or High for stormwater exposure, and 10% for groundwater. 83% of lots have yard area that legally qualifies for on-site infiltration. Ground elevation is typically 39 ft. The median building dates to 1900. 38% of parcels sit over a historic stream or pond.

2,042

Properties in sewershed

82.5%

Legally eligible for on-site infiltration

18%

Stormwater exposure: Moderate or High

10%

Groundwater exposure: Moderate or High

What sets RH-016 apart

39 ft

Median ground elevation

76%

Average impervious cover per lot

1900

Median year built

38%

Properties over a historic stream or pond

Stats computed from Flood Form’s NYC parcel data as of October 9, 2026

Common solutions for Cobble Hill 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

All NYC sewersheds →

Want to see where your specific property stands?

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