Sewershed WI-046 · NYC DEP Combined Sewer Overflow Tributary Area
WI-046 - Harlem, Manhattan
Properties in this area share the WI-046 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 Harlem, Manhattan specifically.
WI-046 is a combined sewer area covering 1,534 properties in Harlem, Manhattan. Flood Form rates 35% of them Moderate or High for stormwater exposure, and 44% for groundwater. 65% of lots have yard area that legally qualifies for on-site infiltration. Ground elevation is typically 40 ft. The median building dates to 1906. 33% of parcels sit over a historic stream or pond.
1,534
Properties in sewershed
65%
Legally eligible for on-site infiltration
35%
Stormwater exposure: Moderate or High
44%
Groundwater exposure: Moderate or High
What sets WI-046 apart
40 ft
Median ground elevation
90%
Average impervious cover per lot
1906
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 Harlem 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
- NR-056Sugar Hill588 properties · 18% with Moderate or High stormwater exposure
- WI-045Harlem528 properties · 25% with Moderate or High stormwater exposure
- NR-002Sugar Hill156 properties · 38% with Moderate or High stormwater exposure
- NR-003Washington Heights403 properties · 30% with Moderate or High stormwater exposure
- WI-064Concourse213 properties · 43% with Moderate or High stormwater exposure
- WI-038Harlem671 properties · 30% with Moderate or High stormwater exposure
Want to see where your specific property stands?
Get Your Property’s Flood Form