Photo: ajay_suresh · CC BY 4.0Living in Armonk, NY: what to set up and who to call
North Castle Water District #4 reported 16 health-based violations to EPA in the last five years: a PFAS chemical (PFOA) ×13, manganese ×2, a PFAS chemical (PFOS). 78% of systems its size reported none. Armonk has no town government of its own, so Westchester County runs its elections and most services, and its children attend Byram Hills Central School District.
I’m new in town
What to set up in Armonk, and who provides it. Tap an answer for the details and where they come from.
Power, water and internet
Who to call to start service at a new address in Armonk.
Power comes from Con Edison
Con Edison (Consolidated Edison Co. of New York), an investor-owned utility, serves all of Armonk. Its homes paid an average of 36.7¢ per kWh in 2025, about $137 a month (its average across New York, for customers on its standard service). New York lets you buy power from another supplier; 10% of Con Edison’s home customers do, and Con Edison still delivers it.
Start or move service: coned.com · (800) 752-6633
Service territory: HIFLD Electric Retail Service Territories (map dated Aug 2023). Prices and customers: EIA-861, 2025.
Water comes from North Castle Water District #4
North Castle Water District #4 supplies Armonk: about 25% of residents live in its service area. North Castle Water District #5 serves another 15%. About 64% of homes are outside any mapped community water system, most likely on private wells, which EPA doesn’t regulate. It draws ground water and serves 1,225 people in all.
16 health-based violations reported to EPA in the five years to October 2026: a PFAS chemical (PFOA) ×13, manganese ×2, a PFAS chemical (PFOS), the latest beginning Apr 2026. 78% of the 7,966 systems serving 1,001–3,300 people had none.
The latest lead result on file, the 90th percentile of homes sampled in Jan 2023–Dec 2025, was 2.5 ppb, below the 15 ppb action level that applied. The highest in five years was 4.4 ppb. That’s higher than 78% of similar systems’ latest results.
The system’s full record: EPA ECHO report
EPA SDWIS via Envirofacts (violations pulled Oct 9, 2026) and ECHO (lead samples, 2026Q3); service area: EPA Community Water System Service Area Boundaries v3.0 (EPA’s estimate). Violations are counted by the start of their compliance period. NY5922909.
3 home internet providers serve Armonk
99% of 1,510 addresses can get 100/20 Mbps; 85% can get fiber.
| Provider | Technology | Addresses | Fastest (Mbps) |
|---|---|---|---|
| Verizon | Fiber, Fixed wireless | 96% | 2,300/2,300 |
| Optimum | Cable, Fiber | 94% | 940/35 |
| T-Mobile | Fixed wireless | 41% | 100/20 |
FCC National Broadband Map, as of December 2025. Availability as providers report it, not speeds people get.
We don’t have Armonk’s trash rules yet
Pickup rules, the dump and recycling in Armonk.
Where your child goes to school
Public school districts and the school path by grade.
Armonk is in Byram Hills Central School District.
Test scores and every school: see Schools →U.S. Department of Education, NCES Common Core of Data, 2024–25. Enrollment rules and registration are the district’s.
No town hall: the county runs things
Armonk is unincorporated, so Westchester County is the local government.
Election office: FVAP local election office directory, updated Sep 2025; jurisdictions: EAC EAVS 2024. Registration rules and links: vote.gov, updated Aug 3, 2026.
Armonk is in ZIP code 10504
ZIP codes where Armonk residents live, with the share of the town in each.
| ZIP | Post office name | Share of Armonk | ZIP’s residents in Armonk |
|---|---|---|---|
| 10504 | Armonk, NY | 100% | 54% |
Census 2020 ZIP Code Tabulation Areas, by census block; post office names: GeoNames (CC BY 4.0). ZIPs created since 2020 are missing.
Getting around, the ER and the library
One line each; the subject pages have the rest.
ER: CMS hospital data. Library: IMLS Public Libraries Survey, FY2024.
Questions about living in Armonk
Who supplies Armonk’s drinking water, and has it had violations?
North Castle Water District #4 (EPA ID NY5922909). It reported 16 health-based violations to EPA in the five years to October 2026: a PFAS chemical (PFOA) ×13, manganese ×2, a PFAS chemical (PFOS). 78% of systems its size had none. Its latest lead 90th percentile was 2.5 ppb (Jan 2023–Dec 2025), against a 15 ppb action level.
Who provides electricity in Armonk?
Con Edison (Consolidated Edison Co. of New York), an investor-owned utility. Its homes paid about 36.7¢ per kWh in 2025 (EIA).
What internet providers serve Armonk?
Verizon, Optimum, T-Mobile (FCC, as of December 2025).
What ZIP codes are in Armonk?
10504. Census 2020 ZIP Code Tabulation Areas.
What school district is Armonk in?
Byram Hills Central School District.
How do I register to vote in Armonk?
In New York you can register online until 10 days before Election Day, in person until 10 days before Election Day, or by mail (postmarked 15 days before and received 10 days before). Elections here are run by the Westchester County Board of Elections. Check your registration at voterlookup.elections.ny.gov.
Sources & dates
Every answer above names its source. Here they are with their dates.
- Water: EPA SDWIS (Envirofacts, pulled Oct 9, 2026), ECHO SDWA 2026Q3, EPA CWS Service Area Boundaries v3.0.
- Power: HIFLD Electric Retail Service Territories (map Aug 2023); EIA-861 final 2025.
- Trash: OpenStreetMap, Geofabrik extract of Oct 9, 2026. © OpenStreetMap contributors (ODbL).
- ZIP codes: Census 2020 ZCTA relationship files; GeoNames postal codes (CC BY 4.0).
- Schools: NCES Common Core of Data, 2024–25.
- Registration: vote.gov, updated Aug 3, 2026 (read Oct 10, 2026). Official sites and area codes: Wikidata.
- Election office: FVAP local election office directory (fetched Oct 10, 2026; each record dated), EAC EAVS 2024 jurisdictions; registration and lookup links from vote.gov’s state data, checked Oct 10, 2026.
- Internet: FCC National Broadband Map, as of December 2025.