Middle Island, NY Cesspool & Septic: Sewer, Rules, Grants

Short answer: About 2% of Middle Island lies inside Coventry Manor Sewer District; everywhere else, wastewater stays on the lot.

Middle Island in numbers

Town	Town of Brookhaven
Area	8.28 sq mi
In active sewer district	2% · Coventry Manor Sewer District
In proposed district	0%
Groundwater zone	Zone III 100%
FEMA flood zone	1%
One-family lots / median	1,569 / 0.52 ac
One-family lots outside active sewer districts	about 1,554

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 2% of Middle Island lies inside Coventry Manor Sewer District; everywhere else, wastewater stays on the lot. By parcel count, roughly 1,554 of Middle Island's 1,569 one-family lots sit outside an active district; that is the local cesspool and septic population, before counting unconnected lots inside districts. Neighbouring areas: Gordon Heights (0% sewered, median lot 0.29 ac); Yaphank (under 1% sewered, median lot 0.69 ac); Coram (22% sewered, median lot 0.36 ac). By active-sewer share Middle Island ranks 55 of the 165 Suffolk hamlets and villages we measured.

Groundwater, lots and flood exposure

Groundwater management Zone III: Article 6's minimum lot for a new home on an on-site system here is 40,000 sq ft, unless the density is met another way or an exemption applies. County parcel records show 1,569 one-family lots touching Middle Island, with a median of 0.52 acres (about 22,500 sq ft), below that minimum and the 54th-largest median lot in our Suffolk table. Also mapped: 1% of the land is in FEMA's 1%-annual-chance flood zone; 100% is in a Special Groundwater Protection Area; 34% is Pine Barrens Core; 66% is Pine Barrens Compatible Growth Area.

For most Middle Island 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 Middle Island

Building and electrical permits: Town of Brookhaven
Sewer: Coventry Manor Sewer District
System approvals and grants: SCDHS, 631-852-5700 (permits) / 631-852-5811 (grants)

Frequently asked questions

Is Middle Island on public sewer?

Partly: about 2% is inside Coventry Manor Sewer District; the other 98% relies on cesspools, septic tanks and I/A systems.

Can Middle Island 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 Brookhaven overview, septic grants, replacement rules. More in Brookhaven: Yaphank, Coram, Ridge, Rocky Point.

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 Middle Island?

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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