Short answer: Nassau's health department puts Old Westbury among the North Shore communities without public sewer. Nassau's S.E.P.T.I.C. grant for eligible nitrogen-reducing upgrades is up to $35,000 per its administrator (details below).
Old Westbury in numbers
| Town | Town of North Hempstead (partly Oyster Bay) |
|---|---|
| Status | Incorporated village |
| Area | 8.5 sq mi |
| Sewer (county list) | Not publicly sewered |
| Parcels / median parcel | about 1,595 / 2.00 ac |
| Building permits | Village of Old Westbury |
Area and parcels computed 2026-11-07 from Nassau County GIS (place boundary; all tax parcels touching it, any use). Sewer status from the Nassau County Department of Health list of sewer districts by community, which is by community, not street.
Sewer status and lots
Nassau's health department puts Old Westbury among the North Shore communities without public sewer. About 1,595 tax parcels touch Old Westbury's 8.5 square miles, with a median of 2.00 acres (about 87,100 sq ft). That is the 9th-largest median parcel of the 133 Nassau places we measured, so most lots have room for a replacement system and its setbacks to plan around. Nearby: Westbury (on public sewer, median parcel 0.17 ac); East Hills (not publicly sewered, median parcel 0.35 ac); Roslyn Heights (not publicly sewered, median parcel 0.20 ac).
Grant and permits
Because the county lists Old Westbury outside public sewer, its homes fall in the area Nassau's S.E.P.T.I.C. grant was designed for, subject to the program's property test. Permits come from the Village of Old Westbury; the contractor needs a Nassau County Home Improvement License, and no county rule we found requires an I/A system for an existing home.
For Old Westbury properties, Nassau grant amount and no-stacking details are on the Nassau County overview and Long Island grants guide.
Who handles what in Old Westbury
- Building permits: Village of Old Westbury
- S.E.P.T.I.C. grants: 516-364-5861 ([email protected])
Frequently asked questions
Is Old Westbury on public sewer?
Nassau's health department puts Old Westbury among the North Shore communities without public sewer.
Who issues permits for septic work in Old Westbury?
The Village of Old Westbury building department, with a contractor holding a Nassau County Home Improvement License.
Rules and grant steps: Town of North Hempstead overview, Nassau regulations, S.E.P.T.I.C. details. More nearby: East Hills, Roslyn Heights, Roslyn Estates, Muttontown.
Sources
Each source was re-read on November 7, 2026. Program amounts and rules change; the agency page is the authority.
- Nassau County DOH: Public sewer districts by community
- Nassau County GIS map service (place boundaries, tax parcels)
- Nassau County Soil & Water Conservation District: S.E.P.T.I.C. program (program administrator)
- Nassau County: S.E.P.T.I.C. program
Need cesspool or septic work in Old Westbury?
Submit a request with your address. We match it to an independent operator with a Nassau County Home Improvement License who serves that address; the operator confirms the time and price with you.
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