Sewershed NR-003 · NYC DEP Combined Sewer Overflow Tributary Area
NR-003 - Washington Heights, Manhattan
Properties in this area share the NR-003 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 Washington Heights, Manhattan specifically.
NR-003 is a combined sewer area covering 403 properties in Washington Heights, Manhattan. Flood Form rates 30% of them Moderate or High for stormwater exposure, and 26% for groundwater. 58% of lots have yard area that legally qualifies for on-site infiltration. Ground elevation is typically 139 ft. The median building dates to 1911. 13% of parcels sit over a historic stream or pond.
403
Properties in sewershed
57.6%
Legally eligible for on-site infiltration
30%
Stormwater exposure: Moderate or High
26%
Groundwater exposure: Moderate or High
What sets NR-003 apart
139 ft
Median ground elevation
91%
Average impervious cover per lot
1911
Median year built
13%
Properties over a historic stream or pond
Stats computed from Flood Form’s NYC parcel data as of October 9, 2026
Common solutions for Washington Heights 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-051Washington Heights258 properties · 36% with Moderate or High stormwater exposure
- NR-002Sugar Hill156 properties · 38% with Moderate or High stormwater exposure
- NR-056Sugar Hill588 properties · 18% with Moderate or High stormwater exposure
- WI-046Harlem1,534 properties · 35% with Moderate or High stormwater exposure
- NR-004Washington Heights297 properties · 49% with Moderate or High stormwater exposure
- WI-061Highbridge296 properties · 48% with Moderate or High stormwater exposure
Want to see where your specific property stands?
Get Your Property’s Flood Form