Short answer: About 6% of the Town of Riverhead's land is inside an active sewer district on the county map, mostly Riverhead Sewer District; about 9,766 of 11,170 one-family lots in the town's hamlets and villages sit outside any active sewer district. There is no town septic rebate, so the county and state grants are the funding.
Last updated: November 2026. Data computed 2026-11-07 from Suffolk County GIS; rules and programs re-read November 7, 2026.
Town of Riverhead in numbers
| Land in active sewer districts | 6% |
|---|---|
| Land in proposed districts | 0% |
| Places with ~0% active sewer | 5 of 7 hamlets and villages |
| One-family lots outside active districts | about 9,766 of 11,170 |
| Groundwater zones (land share) | Zone III about 53%; Zone IV about 36%; Zone VIII about 12% |
| I/A systems installed (Oct 2024) | about 90, 2% of the county's 5,344; 9th of the ten towns |
| Town septic rebate | No |
| Town code on I/A systems | None found beyond the county rules |
Sewer districts and where the cesspools are
- Active districts (2): Riverhead Sewer District (about 5%), Calverton Sewer District (about 1%).
By one-family lot count, the most lots outside an active district are in Wading River (about 2,680), Riverhead (about 2,221), Baiting Hollow (about 1,308), Aquebogue (about 970), Jamesport (about 944). Median one-family lots run from 0.24 acres in Riverhead to 0.67 acres in Northville. In 2 of 7 places the median lot is smaller than Article 6's minimum for a new home on an on-site system in its main zone. Across the town, about 4% of the land is in FEMA's 1%-annual-chance flood zone; 67% is in a Special Groundwater Protection Area; 28% is in the Central Pine Barrens (core plus compatible growth area).
What the Town of Riverhead adds
- Rebate: none listed by the county as of November 7, 2026.
- Town code: no town-wide I/A mandate found beyond the county rules as of November 7, 2026.
- Building department: Town of Riverhead.
Every hamlet and village in the Town of Riverhead
Land-area shares inside county sewer-district polygons; zone = main Article 6 groundwater zone; flood = FEMA 1%-annual-chance zone; lot = median one-family lot (acres). Linked names have their own page. Some village-run systems are missing from the county layer. Full table: sewer coverage by hamlet.
| Hamlet / village | Active sewer | Proposed sewer | Zone | Flood | Median lot (ac) |
|---|---|---|---|---|---|
| Aquebogue | 0% | 0% | Zone IV | 10% | 0.57 |
| Baiting Hollow | 0% | 0% | Zone VIII | 3% | 0.53 |
| Calverton | 6% | 0% | Zone III | 4% | 0.55 |
| Jamesport | 0% | 0% | Zone IV | 7% | 0.46 |
| Northville | 0% | 0% | Zone IV | 2% | 0.67 |
| Riverhead | 18% | 0% | Zone IV | 3% | 0.24 |
| Wading River | 0% | 0% | Zone VIII | 4% | 0.58 |
County rules apply on top: no cesspool-for-cesspool replacement since July 1, 2019, and an I/A system for new homes and major reconstruction since July 1, 2021. Details, licensing and grants: Suffolk County overview.
Frequently asked questions
How much of the Town of Riverhead is on sewer?
About 6% of the land in the town's hamlets and villages is inside an active county sewer district, and 0% inside proposed districts; about 9,766 of 11,170 one-family lots in the town's hamlets and villages sit outside any active sewer district. A district boundary is not a connection.
Does the Town of Riverhead have a septic rebate?
No town rebate is listed by Suffolk County as of November 7, 2026. Riverhead homeowners use the county grant (up to $20,000) and the state grant (up to $25,000); the town had about 90 I/A systems by October 2024.
Who issues building permits for septic work in Riverhead?
The Town of Riverhead building department. SCDHS approves the sanitary system itself.
Sources
Each source was re-read on November 7, 2026. Program amounts and rules change; the agency page is the authority.
- Suffolk County GIS Viewer map service (hamlets, villages, sewer districts, groundwater zones, flood zones, tax parcels)
- Suffolk County DHS presentation, 11/19/2024 (hosted by the Town of Shelter Island)
- Suffolk County DHS: Changes to wastewater practices effective July 1, 2019
- Suffolk County: Septic Improvement Program information
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