Short answer: About 1% of Deer Park lies inside SCCRI Carlls River Wyandanch Sewer District; everywhere else, wastewater stays on the lot. 98% sits in a proposed sewer district, which can rule out the septic grants.
Deer Park in numbers
| Town | Town of Babylon |
|---|---|
| Area | 6.17 sq mi |
| In active sewer district | 1% · SCCRI Carlls River Wyandanch Sewer District |
| In proposed district | 98% · Unfunded Carlls River, Deer Park Avenue Corridor, Unfunded Carlls River 110-3 and 4 |
| Under feasibility study (not a district) | under 1% |
| Groundwater zone | Zone I 65%, Zone VII 35% |
| FEMA flood zone | 0% |
| One-family lots / median | 11 / 0.77 ac |
| One-family lots outside active sewer districts | about 11 |
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 1% of Deer Park lies inside SCCRI Carlls River Wyandanch Sewer District; everywhere else, wastewater stays on the lot. About 98% of Deer Park is inside proposed districts (“Unfunded Carlls River”, “Deer Park Avenue Corridor”, “Unfunded Carlls River 110-3 and 4”). Suffolk's septic grants exclude homes in a proposed sewer district, so check the address on the county map before budgeting for an I/A upgrade. By parcel count, roughly 11 of Deer Park's 11 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: Baywood (0% sewered, median lot 0.37 ac); North Babylon (69% sewered, median lot 0.70 ac); Wyandanch (32% sewered). By active-sewer share Deer Park ranks 58 of the 165 Suffolk hamlets and villages we measured.
Groundwater, lots and flood exposure
Groundwater management Zone I (65%) and Zone VII (35%): 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 11 one-family lots touching Deer Park, with a median of 0.77 acres (about 33,700 sq ft), above that minimum and the 25th-largest median lot in our Suffolk table. 14% is in a Special Groundwater Protection Area.
Before planning an I/A upgrade in Deer Park, confirm whether your street is in the proposed district; if it is, the county and state grants may not apply.
Who handles what in Deer Park
- Building and electrical permits: Town of Babylon
- Sewer: SCCRI Carlls River Wyandanch Sewer District
- System approvals and grants: SCDHS, 631-852-5700 (permits) / 631-852-5811 (grants)
Frequently asked questions
Is Deer Park on public sewer?
Partly: about 1% is inside SCCRI Carlls River Wyandanch Sewer District; the other 99% relies on cesspools, septic tanks and I/A systems.
Can Deer Park homeowners get septic grants?
Many can't: about 98% of Deer Park is inside a proposed sewer district, and the Suffolk and state grants exclude homes there. Homes outside it can apply for up to $20,000 from Suffolk and up to $25,000 from the state. Check the address on the county's eligibility map.
County rules, licensing and grant steps: Town of Babylon overview, septic grants, replacement rules.
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 Sanitary Code, Article 6 (amended 12/1/2020)
- Suffolk County: Septic Improvement Program information
- Suffolk County: SIP property eligibility lookup
Need cesspool or septic work in Deer Park?
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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