Verified as of September 16, 2026. We re-check these pages quarterly.
The county's Septic Improvement Program — everyone calls it SIP — pays up to $20,000 per property toward replacing a cesspool or septic system with an innovative/alternative onsite wastewater treatment system. How much you get depends on whether and how your project qualifies; $20,000 is the ceiling, not a flat rate.
It is not a reimbursement
This is the part homeowners most often get wrong, and it is worth being blunt about. The county does not pay you back. Grant funds are paid directly to your installer, and only after the installation is complete and certified. You never front the grant portion and wait for it.
Two things follow. You must choose an installer from the County Approved Installer List — only vendors on that list may install a grant-funded system. And you must apply and be issued a grant before the system is installed. A system already in the ground cannot be funded retroactively.
Where the money comes from
SIP is funded by the Suffolk County Water Quality Restoration Act, the voter-approved eighth-penny sales tax that took effect in 2025. The county reported in June 2026 that the tax had generated more than $67 million since inception: ten percent goes to administration, and the rest is split between I/A installations and sewers.
That matters for one practical reason. This is a funded program with a revenue stream behind it, not a one-off appropriation waiting to run dry — but it is still finite, and the county has said it needs to reach 5,000 installations a year to make a real dent in the 300,000-plus outdated systems still in the ground.
Worked example
An approved installer quotes $25,000 for an I/A system — roughly the county's own average figure for a nitrogen-removing system, before engineering and design.
- Installer quote: $25,000
- County SIP grant, paid direct to the installer: up to $20,000
- What you would owe the installer: $5,000
- Plus, separately and out of pocket: permit application fees, engineering and design, and landscaping afterward
That is the county grant on its own. In practice most homeowners are also taking the state grant through the same application, which changes the arithmetic again — see stacking the two to $45,000. Your installer confirms the actual split against your approved plans.
What the grant also buys
The SIP grant funds the first three years of the annual professional maintenance the county requires on a grant-funded system. After that the contract is yours, and on the East End the Peconic Estuary Partnership reimburses up to $500 a year toward it.
What an I/A system costs to run
The conditions attached afterward
A grant-funded system stays under county oversight. Annual professional maintenance is required for the life of the system, the Department of Health Services oversees compliance, and the system cannot be removed without prior written approval from the county. None of that is onerous, but it is a permanent commitment and you should know about it before you sign, not after.
Applying
The application is online at suffolkcountyny.gov/septicgrants and the county rebuilt it in 2026 to run on a phone — the deputy county executive said in June that it now takes people about three minutes. Have your current town-issued property tax bill ready, and any evidence of system failure: photographs, service receipts. Where you genuinely do not know something, the form now lets you say so.
Questions go to the county grants team on 631-852-5811 or [email protected]. The county says it responds in about a week.
Verified as of September 16, 2026. We re-check these pages quarterly. The $20,000 ceiling, the direct-payment mechanism, the approved-installer requirement, the apply-before-installing rule and the three years of maintenance were confirmed against Suffolk County's own Septic Improvement Program page and its 2026 homeowner process overview on that date. The county's own disclaimer applies: the program is subject to change. Confirm current availability before counting on a number.
All work is performed by local licensed, permitted Suffolk County-approved installers.