Cesspool Replacement Islip, NY | Grants, Sewers & Costs

Grant money available in Islip

Suffolk County

Up to $20,000

Suffolk County SIP grant. Checked Oct 20, 2026.

New York State

Up to $25,000

NYS SSRP grant. Checked Oct 20, 2026.

Full County and State rules, the 8-step process and a grant estimator are on the Suffolk septic grant guide.

Not a government website. We aren't affiliated with Suffolk County, Nassau County, any town, or New York State, and we can't approve or speed up a grant. Grants go through the official programs, Suffolk SIP (Reclaim Our Water) and Nassau SEPTIC, and the installer you hire handles the grant process with you.

No Town rebate (as of our last check)

We looked for a separate Town of Islip septic rebate and didn't find one (checked 2026-10-19). That means the County and State grants are the money available here. If the Town starts a program, we'll add it.

The Great South Bay is the reason

A 2011 study in the Journal of Coastal Research attributed 69% of the nitrogen in the Great South Bay to cesspools and septic systems. Low-lying neighborhoods south of Montauk Highway in Bay Shore, Islip, East Islip, Oakdale, Sayville and West Sayville have shallow groundwater with a short trip to the bay, so they score well for grant priority and are more likely to need a pressurized shallow drainfield.

Check for sewers first in the western hamlets

Suffolk's Southwest Sewer District (District 3) covers parts of the Towns of Islip and Babylon, and the County's Carlls River sewer expansion reaches into West Islip. Homes in an existing or proposed sewer district can't get the septic grant, so confirm your street before paying for a design.

Brentwood and Central Islip: older cesspools, smaller lots

North of Sunrise Highway, much of Brentwood and Central Islip was built in the postwar boom, before Suffolk banned cesspools in new construction in 1973, so original cesspools are common. On tighter lots, where the driveway, house and property lines sit relative to the old rings decides where a new tank and leaching can go, and that's a design question to raise early.

Installers near Islip

SIP-approved installers on the County's September 2026 list are based in Islandia, Central Islip and Bohemia, inside the town. We don't publish or rank them. When you send a request, it goes to licensed installers who serve your area, and only SIP-approved ones for grant jobs.

Communities covered

Bay Shore
Islip
East Islip
West Islip
Brightwaters
Islandia
Great River
Oakdale
Sayville
West Sayville
Bayport
Bohemia
Holbrook (part)
Ronkonkoma (part)
Central Islip
Brentwood
Hauppauge (part)

Incorporated villages run their own building departments. Your design professional identifies any village permits.

Services in Islip

Island-wide prices: cesspool replacement cost guide.

Islip cesspool & septic FAQ

I'm in West Islip. Am I in a sewer district?

Possibly. The Carlls River sewer expansion covers parts of West Islip, and the Southwest Sewer District covers parts of the town. Check your address with the County before you apply for a septic grant.

Does the Town of Islip have its own septic rebate?

Why does my Sayville or Oakdale cesspool fill up so fast?

Shallow groundwater. When the water table is close to the bottom of the rings, there's little room for effluent to drain, especially after rain or at high tide. It's also a sign the grant's failure documentation could help you: save pumping receipts.

Cesspool replacement in the Town of Islip