Sewershed RH-030 · NYC DEP Combined Sewer Overflow Tributary Area
RH-030 - Carroll Gardens, Brooklyn
Properties in this area share the RH-030 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 Carroll Gardens, Brooklyn specifically.
RH-030 is a combined sewer area covering 482 properties in Carroll Gardens, Brooklyn. Flood Form rates 40% of them Moderate or High for stormwater exposure, and 50% for groundwater. 65% of lots have yard area that legally qualifies for on-site infiltration. Ground elevation is typically 22 ft. The median building dates to 1910. 56% of parcels sit over a historic stream or pond.
482
Properties in sewershed
64.5%
Legally eligible for on-site infiltration
40%
Stormwater exposure: Moderate or High
50%
Groundwater exposure: Moderate or High
What sets RH-030 apart
22 ft
Median ground elevation
84%
Average impervious cover per lot
1910
Median year built
56%
Properties over a historic stream or pond
Stats computed from Flood Form’s NYC parcel data as of October 9, 2026
Common solutions for Carroll Gardens 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-031Carroll Gardens324 properties · 35% with Moderate or High stormwater exposure
- RH-035Carroll Gardens815 properties · 23% with Moderate or High stormwater exposure
- RH-028Red Hook647 properties · 47% with Moderate or High stormwater exposure
- RH-019Cobble Hill352 properties · 25% with Moderate or High stormwater exposure
- RH-016Cobble Hill2,042 properties · 18% with Moderate or High stormwater exposure
- RH-018Cobble Hill242 properties · 33% with Moderate or High stormwater exposure
Want to see where your specific property stands?
Get Your Property’s Flood Form