Geothermal Heating & Cooling on Long Island: The Complete 2026 Guide (Costs, Rebates & What Changed)

If you've been watching energy costs climb on Long Island and quietly wondering whether geothermal is finally worth it — 2026 is the year to make that decision with open eyes. Because two significant things changed at the start of this year, and both of them affect what geothermal costs, how much you can save, and why the conversation is more urgent than it's been in years.

What changed going into 2026:

First, the federal Section 25D Residential Clean Energy Credit — which gave homeowners a 30% tax credit on geothermal installations, often worth $9,000 or more — expired on December 31, 2025 under the One Big Beautiful Bill Act. For homeowners who installed systems in 2025, the credit can still be claimed on 2025 tax returns. For new 2026 installations, it's gone.

Second, New York State and PSEG Long Island responded by expanding their own incentive programs significantly, with PSEG rolling out its most aggressive geothermal rebate tiers ever effective January 1, 2026. For many Long Island homeowners, the new state and utility incentives more than replace what the federal credit provided.

And third — starting in 2026, New York State building codes require heat pump systems in all new residential construction. Geothermal is the most efficient heat pump technology available. For anyone building new on Long Island, it's no longer a question of whether to install a heat pump — it's a question of which kind.

This guide covers everything Long Island homeowners, builders, and property owners need to know about geothermal in 2026: how the systems work, what they cost, every incentive still available, the critical role of well drilling in system performance, the Long Island-specific permits and regulations, and how to find the right contractor team for the job.

What Is Geothermal Heating and Cooling — and Why Does It Work So Well on Long Island?

Geothermal heating and cooling — also called ground source heat pump (GSHP) technology — uses the earth's stable underground temperature to heat and cool buildings far more efficiently than any conventional HVAC system.

Here's the core principle: regardless of what's happening above ground — whether it's a January nor'easter or a 95-degree August afternoon — the ground below about 15 to 20 feet maintains a remarkably consistent temperature year-round. On Long Island, that stable groundwater temperature is approximately 50°F to 55°F. A geothermal heat pump exploits that constant temperature through a loop of fluid that exchanges heat between the building and the ground.

In winter, the system extracts heat from the earth and moves it inside your home. In summer, the process reverses — excess heat from inside your home is transferred to the cooler ground below. The same system handles both heating and cooling, and many systems can also supply domestic hot water through a component called a desuperheater.

Why Long Island is exceptional for geothermal:

Long Island's geology is unusually favorable for geothermal performance. The island sits atop a highly productive sole-source aquifer system with groundwater temperatures of 50°F to 55°F — consistent, abundant, and well-suited to efficient heat exchange. The sandy, porous soils that make Long Island's aquifer so productive also make drilling easier and less expensive than regions with hard bedrock geology. And the island's climate — with meaningful heating loads in winter and significant cooling demand in summer — means a geothermal system gets used heavily year-round, maximizing the return on investment.

NYSERDA's own field monitoring study of 33 ground source heat pump systems installed in Long Island homes found a seasonal average heating COP (Coefficient of Performance) of 3.8 — meaning the systems delivered 3.8 units of heat for every unit of electricity consumed. That's roughly 280% to 380% more efficient than conventional electric resistance heating, and significantly more efficient than air-source heat pumps operating in cold weather.

The 2026 Incentive Picture: What's Gone, What Replaced It, and How to Stack Everything

This is the section most Long Island homeowners want to read first. Here is the complete, current incentive picture for 2026 geothermal installations in Nassau and Suffolk Counties.

What Expired: The Federal Section 25D Credit

The federal Section 25D Residential Clean Energy Credit, which provided a 30% tax credit on the full installed cost of a geothermal system with no dollar cap, expired at the end of 2025. A $30,000 geothermal installation that previously generated a $9,000 federal credit no longer qualifies for that credit if work begins in 2026.

If you installed or began a qualified system before December 31, 2025, you can still claim the credit on your 2025 federal tax return using IRS Form 5695. Unused credits from 2025 may carry forward to future tax years.

This is real money that's no longer available. We won't minimize that. But here's the rest of the story.

What's Still Active — and Got Bigger

1. PSEG Long Island Geothermal Rebate — Now Up to $2,400 Per Ton

PSEG Long Island administers rebates on behalf of the Long Island Power Authority, and their 2026 geothermal rebate program is the most aggressive they've offered. The rebate is $2,400 per heating ton for qualifying ground source heat pump systems. For a typical 3-ton residential system, that's $7,200 back from PSEG — before any other incentives.

Income-eligible customers (at or below 80% AMI) qualify for double the standard rebate — $4,800 per ton — meaning a 3-ton system generates $14,400 from PSEG alone.

An additional $250 rebate is available when a qualifying desuperheater is installed along with an electric tank storage water heater.

Key PSEG requirements:

• Systems must be properly sized per AHRI standards and NY State Clean Heat Calculator

• Equipment must meet efficiency thresholds (EER and COP requirements vary by system type and staging)

• Pre-approval is required before work begins — your contractor submits the application

• Installation must be by a participating NYS Clean Heat contractor

2. NY State Geothermal Tax Credit — 25% Up to $10,000

New York State's geothermal tax credit was expanded by Governor Hochul in 2025. The credit covers 25% of qualified geothermal system equipment expenditures, now capped at $10,000 (up from the previous $5,000 cap). This is a dollar-for-dollar reduction in your New York State income tax liability — meaning a $40,000 system installation generates a $10,000 state tax credit.

This credit applies to both new installations and retrofits, covers the equipment cost component of the system, and can be carried forward to future tax years if it exceeds your tax liability in the year of installation.

3. NYS Clean Heat Program — Up to $25,000 for Geothermal

The NYS Clean Heat Program, administered by NYSERDA and implemented through utilities including PSEG Long Island, provides additional rebates for geothermal installations. For Long Island specifically, geothermal rebates through the Clean Heat program can reach $25,000 for full fossil fuel decommissioning projects — where an oil or gas heating system is removed and replaced entirely by the geothermal system.

The highest rebate tiers are triggered by full fossil fuel decommissioning — removing the existing boiler, oil tank, and all fossil fuel heating infrastructure and replacing it entirely with geothermal. If you're heating with oil (which a large percentage of Long Island homes still do), this full replacement scenario qualifies for the highest incentive tier.

4. NY State Low-Interest Financing — GJGNY Program

NYSERDA's Green Jobs Green New York (GJGNY) program offers low-interest financing for qualifying geothermal projects, allowing homeowners to finance the installation and repay over time through their utility bill. Interest rates are partially based on area median income, with reduced rates available for income-qualified households. This program removes the barrier of large upfront installation costs for homeowners who qualify for the rebates but need help with the initial outlay.

5. NYSERDA EmPower+ — Up to $24,000 for Income-Qualified Households

For income-eligible households at or below 80% AMI, the EmPower+ program through NYSERDA can provide up to $24,000 toward heat pump installation including geothermal systems. This program stacks with the PSEG enhanced rebate for income-eligible customers, creating a substantial combined incentive package for qualifying homeowners.

How Geothermal Systems Work on Long Island: Open Loop vs. Standing Column vs. Closed Loop

Long Island's aquifer geology creates different options for how geothermal systems are configured compared to other parts of New York State. Understanding the differences is important because the system type affects both cost and performance.

Open-Loop Systems (Most Common on Long Island)

An open-loop geothermal system draws groundwater from a supply well, passes it through the heat pump's heat exchanger where thermal energy is extracted or deposited, and then returns the water to the aquifer through a separate return (injection) well. The water itself is never consumed — it's simply used as a heat exchange medium and returned to the ground.

Open-loop systems are the most common configuration on Long Island because the island's highly productive Magothy aquifer provides abundant groundwater at the consistent 50°F to 55°F temperatures that geothermal systems use. The aquifer's hydraulic conductivity — the ease with which water moves through it — is excellent across much of Nassau and Suffolk Counties, making open-loop systems efficient and high-performing.

Key design consideration — thermal breakthrough: In open-loop systems, the supply and return wells must be separated by adequate distance to prevent "thermal breakthrough" — the phenomenon where the return water (now warmer or cooler depending on the season) influences the temperature of the water being drawn from the supply well. A well-designed open-loop system accounts for Long Island's groundwater flow direction and places wells at appropriate separation distances based on the system's flow rate and the local aquifer's hydraulic conductivity.

Permitting: Open-loop geothermal systems capable of producing more than 45 gallons per minute in Nassau, Suffolk, Kings, and Queens counties require a Part 602 permit from NYSDEC's Region 1 office in Stony Brook, filed before drilling begins. All open-loop and standing column geothermal wells require the driller to be NYSDEC-registered, with preliminary notice and well completion reports filed with the Division of Water.

Standing Column Wells

A standing column well is a variation of the open-loop concept where a single deep well serves as both supply and return. Water is drawn from the bottom of the well column, passes through the heat exchanger, and is returned to the top of the same well. The water migrates down through the column, exchanging heat with the surrounding geology as it descends, and is drawn again from the bottom.

Standing column wells are typically deeper than standard open-loop wells and are most effective in settings with some bedrock presence to provide heat exchange surface area. On

Long Island, standing column wells are less common than open-loop systems due to the island's deep bedrock, though they are used in some applications — particularly on the North Shore where bedrock is closer to the surface.

Closed-Loop Systems

In a closed-loop system, a sealed loop of piping buried in the ground circulates a heat transfer fluid (typically a water and antifreeze mixture) that absorbs or releases heat with the surrounding soil. Unlike open-loop systems, no groundwater is withdrawn or returned — the loop is entirely sealed.

Closed-loop systems can be installed vertically (boreholes drilled straight down) or horizontally (trenches dug to 6–8 feet depth across a large land area). On Long Island, horizontal closed-loop systems are less common for two reasons: the island's shallow groundwater table makes horizontal loops impractical in many locations, and the abundant, productive aquifer makes open-loop systems more efficient and cost-effective. However, closed-loop systems are the right choice for properties where open-loop permitting is restricted or where groundwater quality concerns exist.

Regulatory note: Closed-loop geothermal wells up to 500 feet deep have been specifically exempted from the same registration and reporting requirements that apply to open-loop and standing column wells, following 2023 and 2024 legislative changes. Closed-loop wells deeper than 500 feet are regulated by NYSDEC's Division of Mineral Resources and require a separate permit.

The Well Drilling Component: Why It Matters More Than Most Homeowners Realize

Here is the piece of the geothermal conversation that HVAC contractors rarely discuss in detail — and that Eastern Environmental Solutions is uniquely positioned to address.

A geothermal system is only as good as the wells that feed it. The heat pump equipment — the unit inside your home — is relatively standardized. What makes or breaks a geothermal installation on Long Island is the hydrogeological design of the well system: the depth of the wells, their diameter, the separation distance between supply and return wells, the pump sizing, and the aquifer zone targeted.

Poorly designed well systems are the leading cause of geothermal underperformance on Long Island. A system with inadequate yield, improper well separation, or insufficient depth for the system's heating and cooling load will deliver underwhelming efficiency, negating the financial and environmental benefits homeowners expect.

What proper geothermal well design involves:

Hydrogeological assessment: Before a single foot of drilling begins, the aquifer conditions at the specific property should be understood. What is the local hydraulic conductivity? What direction does groundwater flow, and at what rate? These factors determine where supply and return wells should be placed and how far apart they need to be to prevent thermal breakthrough. Eastern Environmental Solutions brings genuine environmental and hydrogeological expertise to this assessment — the same expertise we apply to groundwater investigation and remediation projects across Long Island.

Well yield testing: The system's flow demand (expressed in gallons per minute) must be confirmed achievable at the specific drilling location. A 3-ton geothermal system typically requires 6–9 GPM of groundwater flow. A 5-ton system may require 10–15 GPM or more. Confirming the aquifer can deliver the required yield at your property before finalizing the system design prevents expensive surprises.

Proper well construction: Geothermal wells are constructed to NYSDEC water well contractor standards, with appropriate casing, grouting, and pump installation. For open-loop systems, both the supply well and the return (injection) well must be properly designed and constructed — the return well must be capable of accepting the full system flow rate without becoming pressurized or causing surface discharge.

Drilling method matters: Eastern Environmental Solutions' Geoprobe® fleet and rotary sonic drilling capabilities allow us to drill geothermal wells with precision while simultaneously characterizing the aquifer — collecting formation samples and groundwater data as we drill. This gives us real-time information to confirm we're targeting the optimal aquifer zone and achieving the required yield. General well drillers drilling geothermal wells without this capability are essentially drilling blind.

What Does a Geothermal System Cost on Long Island in 2026?

Geothermal is a significant investment. Here is an honest breakdown of what Long Island homeowners should expect to budget in 2026, before incentives.

Total System Cost (Before Incentives):

For a typical residential geothermal installation on Long Island — including the heat pump equipment, well drilling, loop piping, distribution system modifications, and permits — total installed costs generally range from:

• Small homes (2–3 tons): $25,000–$40,000

• Medium homes (3–5 tons): $35,000–$65,000

• Larger homes (5+ tons): $50,000–$90,000+

New York State's own geothermal installation cost data indicates average residential installation costs between $20,000 and $35,000 depending on system type and scope, though Long Island's higher labor costs and permitting complexity often push projects toward the upper end of that range or above it.

What drives cost on Long Island specifically:

Well drilling: Open-loop systems require at minimum two wells — supply and return. On Long Island, each well typically costs $7,000–$12,000 depending on depth and diameter. Total well system cost for a residential open-loop installation generally runs $15,000–$30,000, depending on the number of wells, depths, and pump requirements.

Heat pump equipment: Quality ground source heat pump units for residential applications range from $5,000–$15,000 depending on capacity, staging (single vs. multi-stage vs. variable speed), and features. Variable speed units cost more upfront but deliver meaningfully better efficiency and comfort.

Distribution system: If your home currently uses forced hot air, connecting a geothermal system is relatively straightforward. If you heat with steam or hot water radiators (common in older Long Island homes), the distribution system may need modifications or supplemental components to work efficiently with geothermal's lower supply temperatures. This can add $3,000–$10,000+ to the project.

Permits and engineering: Permitting for open-loop geothermal on Long Island includes NYSDEC registration and filing requirements, county health department coordination where applicable, and the Part 602 permit for high-capacity systems. Permitting and engineering costs add $1,000–$3,000 to most projects.

Is Geothermal Right for Your Long Island Property?

Geothermal is not the right fit for every property. Here's an honest assessment of the factors that make a Long Island home a strong geothermal candidate — or a poor one.

Strong candidates:

• Homes currently heating with oil or propane, where annual fuel costs are high and the fossil fuel decommissioning rebate applies

• Properties with adequate lot size to accommodate well drilling and return well placement

• New construction — geothermal well systems are most cost-effectively installed before landscaping and hardscaping are complete, and NY's 2026 building code heat pump mandate makes this increasingly standard

• Homes with forced hot air distribution that can efficiently accept geothermal's supply temperatures

• Homes in PSEG Long Island territory where rebates are most generous

Considerations that require evaluation:

• Older homes with steam or high-temperature hot water heating — distribution system modifications may be needed; feasibility depends on the specific system

• Smaller lots where well separation distances for open-loop systems may be constrained by setback requirements

• Properties near known groundwater contamination — a hydrogeological assessment is essential before drilling for any well purpose on such properties

• Homes already on efficient natural gas heating with low energy bills — payback periods are longer when displacing cheap fuel

The 2026 building code angle: New York State's 2026 requirement that new homes use heat pump systems makes the geothermal conversation especially relevant for anyone building new or undertaking a major renovation. Since heat pump equipment is now a code requirement for new construction, the choice becomes which type of heat pump — and geothermal's superior efficiency, longer equipment lifespan, and silent operation make it the premium choice for those who can accommodate the well installation.

Long Island Geothermal Permitting: What You Need to Know

Geothermal well installation on Long Island involves more permitting than most homeowners expect. Here's a clear summary of what's required:

NYSDEC Water Well Contractor Registration (ECL §15-1525): All drilling of open-loop and standing column geothermal wells must be performed by a NYSDEC-registered water well contractor. Registration requires passing appropriate certification exams and annual renewal. The driller must file a Preliminary Notice with NYSDEC before drilling begins and a Well Completion Report upon project completion.

Part 602 Permit (Open-Loop/Standing Column Systems >45 GPM): In Nassau, Suffolk, Kings, and Queens counties, any open-loop or standing column geothermal system capable of producing more than 45 gallons per minute — including systems drilled up to 500 feet deep — requires a Part 602 permit from NYSDEC's Region 1 office in Stony Brook. The permit application must be filed before drilling begins and includes system design documentation, well location plans, and hydrogeological information.

NYSDEC Division of Mineral Resources (Systems >500 Feet): Open-loop and standing column geothermal wells drilled deeper than 500 feet fall under NYSDEC's Division of Mineral Resources regulation, requiring a separate permit under ECL Article 23. Following recent legislative changes, closed-loop systems deeper than 500 feet are not subject to these same requirements, though NYSDEC is developing specific regulations for that category.

County Health Department: Nassau and Suffolk County health departments may have jurisdiction over geothermal wells, particularly where groundwater withdrawal is involved. Your contractor should confirm county-level requirements for your specific municipality.

NYS Clean Heat Program Pre-Approval: Before work begins on any project seeking PSEG Long Island or NYS Clean Heat rebates, pre-approval must be obtained through the program. Your participating contractor submits the pre-approval application; work cannot commence until approval is received, or the project may be disqualified from rebates.

The takeaway: Geothermal permitting on Long Island is legitimately complex. Work with a contractor who has demonstrated experience navigating both the drilling permit requirements and the incentive program pre-approval process — not one who learns on your project.

Why Eastern Environmental Solutions for Geothermal Well Drilling

Most geothermal installers on Long Island are HVAC companies. They understand the heat pump equipment well. What they typically don't bring is deep expertise in the hydrogeology of Long Island's aquifer system, environmental well design, or the regulatory framework governing groundwater withdrawal.

Eastern Environmental Solutions brings exactly that expertise — backed by 25+ years as Long Island's leading environmental contractor.

What we deliver that HVAC contractors can't:

Hydrogeological site assessment: We evaluate your property's groundwater conditions — aquifer zone, yield potential, flow direction, and thermal breakthrough risk — before designing your well system. This assessment draws on the same expertise we apply to contamination investigation and remediation projects across Nassau and Suffolk Counties.

Precision drilling with Geoprobe® technology: Our Geoprobe® fleet and rotary sonic and mud drilling capabilities allow us to characterize the aquifer in real-time as we drill — confirming we're in the right formation and achieving the required yield before completing the well installation.

Complete well system installation: Supply wells, return wells, pump installation, pressure systems, and all associated plumbing — fully permitted and documented per NYSDEC and county requirements.

Full permitting management: We handle NYSDEC registration compliance, Part 602 permit applications, preliminary notices, well completion reports, and county health department coordination. You don't navigate the regulatory landscape — we do.

Environmental context: If your property has any history of oil tanks, industrial use, or known groundwater concerns, we can assess those issues as part of the pre-drilling evaluation. Drilling a geothermal well near a contamination source without that assessment is a risk no homeowner should take — and one that Eastern is uniquely positioned to prevent.

📞 Thinking about geothermal for your Long Island home or business? Call Eastern Environmental Solutions at (631) 727-2700 for a free geothermal well consultation. We serve Nassau County, Suffolk County, NYC, NJ, and Upstate New York. Available 24/7. Or request a quote online.

Frequently Asked Questions: Geothermal on Long Island in 2026

Is the 30% federal tax credit still available for geothermal in 2026? No. The Section 25D Residential Clean Energy Credit expired December 31, 2025 under the One Big Beautiful Bill Act. It is no longer available for geothermal systems installed in 2026. However, if your system was installed and operational by December 31, 2025, you can still claim the credit on your 2025 tax return. New York State and PSEG Long Island have both expanded their programs for 2026, and the combined state and utility incentives are competitive with — and in some cases exceed — what was available with the federal credit stacked.

What is the PSEG geothermal rebate for 2026? PSEG Long Island's 2026 rebate for qualifying ground source heat pump systems is $2,400 per heating ton for standard-rate customers. Income-eligible customers receive $4,800 per heating ton. A typical 3-ton residential system qualifies for a $7,200 rebate from PSEG — before any state tax credits or Clean Heat Program rebates.

Do I need to remove my oil heating system to get the highest rebates? To qualify for the highest NYS Clean Heat Program rebate tiers, full fossil fuel decommissioning — removing your existing oil or gas heating system entirely — is typically required. Projects that keep a backup fossil fuel system as a supplemental heat source may qualify for lower rebate amounts. Your contractor's pre-approval application specifies the project scope and determines the applicable rebate tier.

How long does a geothermal installation take on Long Island? A complete geothermal installation — from initial site assessment and permitting through well drilling, equipment installation, and system commissioning — typically takes four to twelve weeks, depending on permitting timelines, contractor availability, and project complexity. Well drilling alone typically takes one to three days for a residential open-loop system. Permitting, particularly the Part 602 permit if required, can take several weeks.

Can geothermal work with my existing radiators or radiant floor heating? Geothermal heat pumps supply water at lower temperatures than conventional boilers — typically 90°F to 110°F rather than 140°F to 180°F. Radiant floor systems are generally compatible at these temperatures. Steam and standard hot water radiator systems may require modifications, oversizing, or supplemental heating elements to perform well with geothermal supply temperatures. A proper Manual J load calculation and distribution system assessment is essential before committing to geothermal if you have radiators.

What is thermal breakthrough and how is it prevented? Thermal breakthrough occurs when the warm or cool water returned to the aquifer through a return well begins affecting the temperature of the water drawn from the supply well. It's prevented through proper well placement — supply and return wells must be separated by adequate distance based on the aquifer's flow rate and direction, and the system's flow demand. Eastern Environmental Solutions' hydrogeological expertise ensures this calculation is done correctly for your specific site.

How long do geothermal systems last? The heat pump equipment inside your home typically lasts 20 to 25 years — considerably longer than conventional HVAC systems. The underground loop or well infrastructure lasts 50+ years with proper installation and maintenance. Unlike a furnace or boiler, a geothermal system has no outdoor components exposed to weather, significantly extending equipment lifespan.

Does geothermal work as air conditioning too? Yes — a geothermal system handles both heating and cooling through the same equipment. In summer, the heat pump extracts heat from your home and deposits it into the cooler ground below. Many Long Island homeowners find that geothermal provides more consistent, comfortable cooling than conventional central air conditioning because the system isn't working against hot outdoor air temperatures.

Eastern Environmental Solutions, Inc. — 258 Line Road, Manorville, NY 11949 | (631) 727-2700 | easternenviro.com Serving Long Island, Nassau County, Suffolk County, NYC, New Jersey & Upstate New York Content current as of June 2026. Incentive programs are subject to change — verify current amounts with PSEG Long Island and NYSERDA before making installation decisions.