Sewershed WI-045 · NYC DEP Combined Sewer Overflow Tributary Area
WI-045 - Harlem, Manhattan
Properties in this area share the WI-045 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-045 is a combined sewer area covering 528 properties in Harlem, Manhattan. Flood Form rates 25% of them Moderate or High for stormwater exposure, and 23% for groundwater. 62% of lots have yard area that legally qualifies for on-site infiltration. Ground elevation is typically 24 ft. The median building dates to 1910. 10% of parcels sit over a historic stream or pond.
528
Properties in sewershed
61.7%
Legally eligible for on-site infiltration
25%
Stormwater exposure: Moderate or High
23%
Groundwater exposure: Moderate or High
What sets WI-045 apart
24 ft
Median ground elevation
87%
Average impervious cover per lot
1910
Median year built
10%
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
- WI-038Harlem671 properties · 30% with Moderate or High stormwater exposure
- WI-046Harlem1,534 properties · 35% with Moderate or High stormwater exposure
- WI-037East Harlem260 properties · 32% with Moderate or High stormwater exposure
- NR-043Harlem2,288 properties · 50% with Moderate or High stormwater exposure
- WI-064Concourse213 properties · 43% with Moderate or High stormwater exposure
- WI-066Mott Haven139 properties · 56% with Moderate or High stormwater exposure
Want to see where your specific property stands?
Get Your Property’s Flood Form