St. James, NY Cesspool & Septic: Sewer, Rules, Grants

Short answer: About 4% of St.

St. James in numbers

Town	Town of Smithtown
Area	4.55 sq mi
In active sewer district	4% · Fairfield @ St. James Sewer District
In proposed district	2% · Lake Avenue Sewer Extension
Groundwater zone	Zone VIII 97%, Zone I 3%
FEMA flood zone	0%
One-family lots / median	4,456 / 0.27 ac
One-family lots outside active sewer districts	about 3,823

Computed 2026-11-07 from Suffolk County GIS (hamlet boundaries, sewer districts, groundwater management zones, FEMA flood zones, protection areas, tax parcels). Shares are of land area; a district boundary is not a hookup, and some village-run systems are missing from the county layer. Method and full table.

Sewer coverage

About 4% of St. James lies inside Fairfield @ St. James Sewer District; everywhere else, wastewater stays on the lot. A sliver (2%) is inside a proposed district (“Lake Avenue Sewer Extension”). By parcel count, roughly 3,823 of St. James's 4,456 one-family lots sit outside an active district; that is the local cesspool and septic population, before counting unconnected lots inside districts. For comparison, the nearest places: Head of the Harbor (0% sewered, median lot 2.02 ac); Stony Brook (28% sewered, median lot 0.39 ac); Lake Grove (4% sewered, median lot 0.30 ac). By active-sewer share St. James ranks 47 of the 165 Suffolk hamlets and villages we measured.

Groundwater, lots and flood exposure

Groundwater management Zone VIII (97%) and Zone I (3%): Article 6's minimum lot for a new home on an on-site system here is 20,000 sq ft, unless the density is met another way or an exemption applies. County parcel records show 4,456 one-family lots touching St. James, with a median of 0.27 acres (about 11,800 sq ft), below that minimum and the 116th-largest median lot in our Suffolk table. No part of St. James is mapped in a flood zone of note, a groundwater protection area or the Pine Barrens.

For most St. James homes the main running cost is pumping; when a cesspool fails, the replacement must include at least a septic tank, and grants can cover most of an I/A system.

Who handles what in St. James

Building and electrical permits: Town of Smithtown
Sewer: Fairfield @ St. James Sewer District
System approvals and grants: SCDHS, 631-852-5700 (permits) / 631-852-5811 (grants)

Frequently asked questions

Is St. James on public sewer?

Partly: about 4% is inside Fairfield @ St. James Sewer District; the other 96% relies on cesspools, septic tanks and I/A systems.

Can St. James homeowners get septic grants?

Yes, if the home isn't sewered and isn't in a proposed sewer district: up to $20,000 from Suffolk and up to $25,000 from the state.

County rules, licensing and grant steps: Town of Smithtown overview, septic grants, replacement rules. More in Smithtown: Nesconset.

Sources

Each source was re-read on November 7, 2026. Program amounts and rules change; the agency page is the authority.

Need cesspool or septic work in St. James?

Submit a request with your address. We match it to an independent, licensed Suffolk County operator who serves that address; the operator confirms the time and price with you.

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