Long Island Septic Grants 2026: Suffolk, Nassau, NYS, Towns

Short answer: Suffolk homeowners can stack a county grant of up to $20,000 and a state grant of up to $25,000 (75% of eligible costs), applied for together, to replace a cesspool or septic system with an I/A system. Nassau's S.E.P.T.I.C. grant is up to $35,000 per the program administrator (the county page still lists $20,000). East Hampton, Southampton and Shelter Island add town rebates. All of them exclude homes already on sewer or inside a proposed sewer district.

Every amount below was read off the program's own page on November 7, 2026. Grants change with budgets and local laws; recheck the linked page before you sign anything.

Every program in one table

Program	Who runs it	Maximum	Who qualifies (short version)	How it pays
Suffolk Septic Improvement Program (SIP)	Suffolk County DHS	Up to $20,000 per property	Existing 1-family, 2-family or 1-family with one accessory apartment; on a cesspool or septic system; not sewered or in a proposed sewer area; valid CO; taxes current, no liens or foreclosure; deed recorded with the County Clerk; OWM-approved I/A project	Assigned to and paid directly to a SIP-approved installer after installation. Not a reimbursement.
NYS Septic System Replacement Program (SSRP), Suffolk	NYS DEC funds; Suffolk DHS administers	Up to 75% of eligible costs, max $25,000	Same county application; DEC sets priority areas (on Long Island, the county Nine Element Plans)	To the installer or as a reimbursement to the owner, after installation
Nassau S.E.P.T.I.C.	Nassau County; administered by the Nassau County Soil & Water Conservation District	Up to $35,000 per the administrator; the county page still lists $20,000 (confirm at 516-364-5861). Includes the state SSRP share, so no separate state grant on top	1- and 2-family homes, not-for-profits, small businesses with design flow ≤ 1,000 gallons/day; I/A installed after March 1, 2018 replacing a cesspool or septic system; valid CO; not connected to sewer or in an existing or proposed district (exceptions below); no open tax liens	Grant; three-year maintenance agreement included in the installation contract
Southampton Town I/A rebate	Town Community Preservation Fund	Base up to $20,000; +$5,000 low-to-moderate income; max $25,000	Property in a Water Quality Improvement Plan priority area (collapsing systems elsewhere may qualify); replacing an existing system; not new construction on vacant land	Rebate after work is complete, about 60 to 90 days after paperwork
East Hampton Town Septic Incentive	Town Community Preservation Fund	$20,000 in the Water Protection District; $15,000 elsewhere; $20,000 for low-to-moderate income	Residential and non-residential owners in the town, including its villages; not new construction	Reimbursement of approved costs; the town can pay the installer directly
Shelter Island WQI rebate	Town Community Preservation Fund	Base up to $12,000 (scored on nitrogen benefit) + $5,000 for a pressurized shallow drainfield + $4,000 if SCDHS mandates moving a private well	Voluntary upgrades and catastrophic cesspool failures; not upgrades mandated by SCDHS or the town code; not tear-down rebuilds	Reimburses eligible costs not already covered by the state and county

Suffolk County: SIP and SSRP

Suffolk raised the county award to $20,000 through Local Law 9-2026, funded by the Water Quality Restoration Fund that voters approved in November 2024 (the added one-eighth of one percent sales tax took effect March 1, 2025). In August 2026 the county opened a new application portal and described the combined county and state maximum as up to $45,000.

The state piece, explained. DEC's program summary allows counties to grant up to 50% of eligible costs (max $10,000) for ordinary septic projects, or 75% (max $25,000) for enhanced projects. Suffolk's grant page states the 75% / $25,000 tier for the I/A replacements it funds.

Who goes first. Applications with a documented system failure are ranked ahead of everyone else: catastrophic failures, then non-catastrophic failures, then homes in the county's Priority Critical Areas (0 to 2 years groundwater travel time to surface water, or groundwater priority area 1), then Critical Areas (2 to 25 years), then everyone else. If you have proof of a failure (photos, pump-out receipts), include it.

What you pay for yourself. Permit application fees, engineering and design, post-installation landscaping and maintenance after the first three years. The county grant covers the first three years of maintenance.

Rules that come with the money. You can't remove or disable a grant-funded system. You must keep it maintained at least once a year by a licensed provider, for as long as you own it.

The proposed-sewer-district catch

Both counties exclude homes inside a proposed sewer district, not just homes already connected. In Suffolk that can rule out whole neighborhoods. On our town pages we measure how much of each hamlet lies inside an active or proposed district on the county's GIS layer: in Deer Park and Sayville, for example, almost all of the land is inside a proposed district. Treat that as a reason to check, not an answer: the county's SIP eligibility lookup is the authority for your address.

Nassau allows two exceptions: a home in an existing district that the district documents can't connect, and, at the county's discretion, a home in a proposed district whose system has documented failure.

Nassau County: S.E.P.T.I.C.

Nassau's Septic Environmental Program to Improve Cleanliness (S.E.P.T.I.C.) pays toward replacing a cesspool or septic system with an approved nitrogen-reducing I/A system, for eligible properties outside existing and proposed sewer districts. The grant is up to $35,000 per the program administrator (Nassau County Soil & Water Conservation District); the county page still lists $20,000; confirm at 516-364-5861. The administrator reports roughly 400 funded upgrades, 186 of them installed as of July 30, 2025.

No double-counting with the state program. In Nassau the state Septic System Replacement Fund is already inside the S.E.P.T.I.C. grant (the county's $20,000 figure is $10,000 of federal ARPA money plus $10,000 of state SSRP money, per NYS EFC), so don't add the $25,000 state amount on top.

The program's FAQ adds details that matter when you plan: the county says conventional cesspools and septic systems on Long Island count as failing for DEC purposes because they can't remove nitrogen, so an old but working system can qualify; you can apply retroactively for a system installed after March 1, 2018, though funding isn't guaranteed; grant money goes first to installation costs and then, if any remains, toward design; sales tax and government permit fees aren't reimbursed; and New York doesn't allow one firm to both design and install, so you'll hire a design professional and a separate installer from the program's list. Installers must hold a Nassau County Home Improvement License. In 2024 the county's FAQ said it had funding for 403 grants, issued first-come, first-served.

Maintenance agreements are required for the life of the system, with proof sent to the county each year; the county estimates about $300 a year. Failing to show a maintenance contract can trigger repayment of the grant. Questions: [email protected] or 516-364-5861.

Not sure whether your Nassau community is sewered? The county health department's district list names the communities it shows as not publicly sewered; we summarize it on the Nassau County page.

Town rebates on the East End

Southampton. Base rebate up to $20,000, plus $5,000 for low-to-moderate income applicants, maximum $25,000. Covers removal of the old system, design, labor and materials, a 3-year maintenance contract and restoration; excludes expediting fees and costs other grants already paid. Final paperwork is due within one year of the county's final approval. Community Preservation office: 631-287-5720.
East Hampton. Up to $20,000 in the Water Protection District, $15,000 elsewhere in town, $20,000 for income-qualified owners; villages inside the town are included. Natural Resources Department, 631-324-0496.
Shelter Island. Scored base grant up to $12,000, plus fixed add-ons for a pressurized shallow drainfield ($5,000) and a county-mandated well relocation ($4,000). The town only reimburses costs the state and county didn't cover, and won't fund an upgrade that SCDHS or the town code required.

Suffolk's grant page lists only these three towns as extra funding sources. For Babylon, Brookhaven, Huntington, Islip, Riverhead, Smithtown and Southold, we found no town septic rebate as of November 7, 2026.

How the money stacks

County SIP and state SSRP come from one Suffolk application and are paid to the installer after the inspection.
Town rebates in Southampton and Shelter Island pay only for costs the county and state grants didn't cover. East Hampton can pay your installer directly and leave any remainder for your other approved costs.
No grant pays for permit fees in Suffolk or Nassau.

For a sense of scale: the median four-bedroom quote on the county's November 2025 installer sheet, for a system that reuses the existing leaching rings, was about $25,700. The county and state maximums together exceed that, but a grant can't pay more than the eligible cost, and design, permits and landscaping stay with you. Prices by scenario are in our cost guide.

How to apply in Suffolk

Check the address on the eligibility map and gather your current town-issued tax bill, plus proof of failure if you have it.
Apply online through the county's Septic Improvement Program page (it files for SIP and SSRP together).
If awarded, e-sign the grant agreement within 30 days.
Hire a design professional; get the OWM permit.
Choose a SIP-approved installer, submit the quote and sign the Assignment of Payment forms.
Install, witnessed start-up, as-built plans, registration and maintenance contract.
The county pays the installer after the inspector's certification.

Full details on each step: the Suffolk I/A permit path. Questions: 631-852-5811 or [email protected].

Frequently asked questions

How much is the Suffolk County septic grant in 2026?

Up to $20,000 per property from the county Septic Improvement Program (Local Law 9-2026 raised the award to $20,000), plus up to 75% of eligible costs capped at $25,000 from the New York State Septic System Replacement Program. One county application covers both.

Can I get the grant if I'm in a proposed sewer district?

Generally no. Suffolk's program requires that the home not be connected to sewer or located within a proposed sewer district, and Nassau's S.E.P.T.I.C. program has the same rule for existing or proposed districts, with narrow exceptions for documented site constraints or failing systems. Check the address on the county's eligibility map before planning around a grant.

Is the Suffolk septic grant a reimbursement?

No. The county SIP grant is assigned to your installer and paid to them after the system is installed and inspected. You must choose an installer from the county's SIP-approved list and you must be issued the grant before installation. The state SSRP portion can be paid to the installer or reimbursed to you.

Does Nassau County have a septic grant?

Yes. S.E.P.T.I.C. helps single- and two-family homes, not-for-profits and small businesses with a design flow up to 1,000 gallons a day replace a cesspool or septic system with an approved nitrogen-reducing system installed after March 1, 2018. The amount is up to $35,000 per the program administrator (Nassau County Soil & Water Conservation District); the county page still lists $20,000; confirm at 516-364-5861. The state SSRP money is already part of the Nassau grant, so it isn't a second layer on top.

Are septic grants taxable?

Nassau County's FAQ says the IRS has determined the S.E.P.T.I.C. grants are a community benefit and that 1099 forms will not be issued. For Suffolk grants, ask SCDHS or a tax professional; we did not find an equivalent statement on the current Suffolk pages.

Which Suffolk towns add their own rebate?

East Hampton, Southampton and Shelter Island, all funded through their Community Preservation Funds. Suffolk County's grant page lists only those three towns as additional funding sources as of November 2026.

Sources

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

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