Sewershed NR-040 · NYC DEP Combined Sewer Overflow Tributary Area
NR-040 - Manhattan Valley, Manhattan
Properties in this area share the NR-040 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 Manhattan Valley, Manhattan specifically.
NR-040 is a combined sewer area covering 1,080 properties in Manhattan Valley, Manhattan. Flood Form rates 33% of them Moderate or High for stormwater exposure, and 29% for groundwater. 64% of lots have yard area that legally qualifies for on-site infiltration. Ground elevation is typically 102 ft. The median building dates to 1910. 37% of parcels sit over a historic stream or pond. According to NYC DEP green infrastructure records, this sewershed drains to East River / Open Waters. NYC DEP has built 5 green infrastructure assets here.
1,080
Properties in sewershed
64.3%
Legally eligible for on-site infiltration
33%
Stormwater exposure: Moderate or High
29%
Groundwater exposure: Moderate or High
What sets NR-040 apart
102 ft
Median ground elevation
94%
Average impervious cover per lot
1910
Median year built
37%
Properties over a historic stream or pond
Stats computed from Flood Form’s NYC parcel data as of October 9, 2026
Common solutions for Manhattan Valley 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-041Morningside Heights207 properties · 39% with Moderate or High stormwater exposure
- NR-038Upper West Side1,521 properties · 35% with Moderate or High stormwater exposure
- WI-024Harlem1,767 properties · 33% with Moderate or High stormwater exposure
- WI-023East Harlem930 properties · 50% with Moderate or High stormwater exposure
- NR-043Harlem2,288 properties · 50% with Moderate or High stormwater exposure
- WI-016Yorkville204 properties · 25% with Moderate or High stormwater exposure
Want to see where your specific property stands?
Get Your Property’s Flood Form