Short answer: Locust Valley has no public sewer collection district on the county health department's list; wastewater is handled on each lot. Nassau's S.E.P.T.I.C. grant for eligible nitrogen-reducing upgrades is up to $35,000 per its administrator (details below).
Locust Valley in numbers
| Town | Town of Oyster Bay |
|---|---|
| Status | Unincorporated hamlet |
| Area | 1.02 sq mi |
| Sewer (county list) | Not publicly sewered |
| Parcels / median parcel | about 1,543 / 0.18 ac |
| Building permits | Town of Oyster Bay |
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
Locust Valley has no public sewer collection district on the county health department's list; wastewater is handled on each lot. About 1,543 tax parcels touch Locust Valley's 1.02 square miles, with a median of 0.18 acres (about 7,700 sq ft). That is the 57th-largest median parcel of the 133 Nassau places we measured. Nearby: Lattingtown (not publicly sewered, median parcel 2.00 ac); Matinecock (not publicly sewered, median parcel 2.63 ac); Mill Neck (not publicly sewered, median parcel 2.95 ac).
Grant and permits
Because the county lists Locust Valley 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 Town of Oyster Bay; 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 Locust Valley properties, Nassau grant amount and no-stacking details are on the Nassau County overview and Long Island grants guide.
Who handles what in Locust Valley
- Building permits: Town of Oyster Bay
- S.E.P.T.I.C. grants: 516-364-5861 ([email protected])
Frequently asked questions
Is Locust Valley on public sewer?
Locust Valley has no public sewer collection district on the county health department's list; wastewater is handled on each lot.
Who issues permits for septic work in Locust Valley?
The Town of Oyster Bay building department, with a contractor holding a Nassau County Home Improvement License.
Rules and grant steps: Town of Oyster Bay overview, Nassau regulations, S.E.P.T.I.C. details. More nearby: Bayville, Glen Head, Sea Cliff, East Norwich.
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 Locust Valley?
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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