Is Your Well Water Safe? PFAS & Groundwater Contamination on Long Island

If your Long Island home runs on a private well, you probably assume your water is clean. It comes from the ground, it's been there for years, and it looks and tastes fine. But here's a fact that should give every Long Island well owner pause: you can't see, smell, or taste the contaminants most likely to be in your water.

Long Island has a serious groundwater contamination problem — one that has been building for decades and is still not fully resolved. The island's sole-source aquifer, which supplies 100% of the region's drinking water, has been impacted by decades of industrial activity, military operations, agricultural runoff, and even everyday household products. The result is a groundwater system that contains measurable levels of some of the most concerning chemicals in modern environmental science — including PFAS "forever chemicals," 1,4-dioxane, volatile organic compounds (VOCs), and more.

For homeowners on public water systems, treatment upgrades by utilities like the Suffolk County Water Authority are addressing many of these issues. But if you're on a private well, you are your own water authority. Nobody is testing your water unless you arrange it yourself. Nobody is treating your water unless you install treatment systems. The responsibility — and the risk — sits entirely with you.

This guide covers what's actually in Long Island's groundwater, which contaminants pose the greatest risk to private well owners, how to get your water tested, and what to do if results come back with problems.

Why Long Island's Groundwater Is Particularly Vulnerable

To understand why Long Island's water contamination problem is so severe, you have to understand how the island's water system works.

Long Island is underlain by a sole-source aquifer — a designation by the EPA that means the region's groundwater is the only drinking water supply available. There are no rivers, reservoirs, or alternative water sources to fall back on. Every drop of water consumed on

Long Island comes from what's in the ground beneath it.

That aquifer system recharges through rainfall percolating down through Long Island's sandy, porous soils. Those same sandy soils that make recharge possible also make contamination easy — chemicals released at or near the surface move quickly and easily through sand, reaching the water table far faster than they would in denser soil or rock environments.

Long Island's history compounds the problem. The post-World War II industrial boom brought aerospace manufacturing, defense contractors, dry cleaners, and chemical plants to Nassau and Suffolk Counties. For decades, industrial waste was routinely discharged directly into the ground — a practice that was either legal or overlooked at the time. The Northrup Grumman facility in Bethpage, the former Grumman naval plant in Calverton, MacArthur Airport in Islip, and dozens of other sites have all contributed to groundwater contamination plumes that continue to migrate through the aquifer system decades later.

Add to that the widespread use of agricultural pesticides across Suffolk County's farming history, the legacy of hundreds of thousands of underground oil tanks throughout Nassau and Suffolk, septic system discharge from millions of residences, and the gradual seepage of everyday household products — and you have a groundwater system under significant stress.

The Main Contaminants Threatening Long Island Well Water

PFAS — "Forever Chemicals"

PFAS (per- and polyfluoroalkyl substances) are a family of thousands of synthetic chemicals that have been used in products ranging from nonstick cookware and firefighting foam to water-resistant clothing and food packaging since the 1940s. They're called "forever chemicals" because they don't break down in the environment — or in the human body — under normal conditions.

The Long Island PFAS situation is severe. A 2025 report by the Environmental Working Group found that at least 189 New York water systems — primarily serving Long Island residents — had detected PFAS above levels set by the EPA's landmark 2024 drinking water standards. The data showed that approximately 702,000 residents in Nassau County and 122,200 in Suffolk County have elevated PFAS levels in their water supplies.

For private well owners, the situation is even more uncertain. Municipal water systems are monitored and regulated. Private wells are not — meaning the PFAS levels in your private well are unknown unless you test specifically for them.

Where does Long Island's PFAS come from?

• Military base firefighting foam (AFFF) used at facilities including Calverton and MacArthur Airport

• Industrial manufacturing and chemical facilities

• Landfills receiving PFAS-containing materials

• Septic systems receiving wastewater from PFAS-containing household products

Health risks of PFAS exposure: PFAS exposure has been linked to immune system dysfunction, thyroid disease, developmental issues in children, increased cholesterol levels, and increased risk of certain cancers including kidney and testicular cancer. The EPA set maximum contaminant levels (MCLs) for PFOA and PFOS at 4 parts per trillion (ppt) in 2024 — among the lowest levels detectable — reflecting how seriously health agencies take these compounds.

Important 2025 update: The future of the federal 4 ppt standard is currently uncertain under the current administration, with compliance deadlines under review. New York State maintains its own standard of 10 ppt for PFOA and PFOS — providing some baseline protection regardless of what happens at the federal level. However, private well owners are not covered by these regulatory standards and must take action independently.

1,4-Dioxane — Long Island's Other "Forever Chemical"

If PFAS gets more headlines nationally, 1,4-dioxane is arguably Long Island's most locally acute contamination crisis. Long Island has some of the highest levels of 1,4-dioxane contamination in the entire United States.

1,4-dioxane is a synthetic chemical that was widely used as a stabilizer for industrial solvents, particularly 1,1,1-trichloroethane (TCA), from the 1950s through the 1990s. It entered Long Island's groundwater primarily through industrial manufacturing operations that routinely disposed of chemical waste directly into the ground. Approximately 70% of Long Island's public water supply wells have detected 1,4-dioxane above the minimum reporting threshold.

Like PFAS, 1,4-dioxane moves freely and rapidly through groundwater and resists conventional treatment. It doesn't bind to soil particles or break down naturally in the environment, allowing it to migrate far from its original release point and persist in aquifers for generations.

Health risks: The EPA classifies 1,4-dioxane as a probable human carcinogen. Long-term exposure through drinking water has been linked to liver and kidney damage and increased cancer risk. New York State has established the strictest enforceable drinking water standard in the nation for 1,4-dioxane at 1 part per billion (ppb) — and has banned most of the household and personal care products that contain it as a manufacturing byproduct.

For private well owners: While public water systems are being upgraded with Advanced Oxidation Process (AOP) treatment to remove 1,4-dioxane, private well owners have no such safety net. Home filtration options for 1,4-dioxane are limited — conventional activated carbon filters have only partial effectiveness, and advanced treatment systems are expensive. Testing is the critical first step.

Volatile Organic Compounds (VOCs) — TCE, PCE & More

Volatile organic compounds are a broad category of industrial chemicals that vaporize at room temperature and have contaminated groundwater across Long Island from decades of industrial use. The most concerning on Long Island include:

Trichloroethylene (TCE): A solvent used extensively in metal degreasing and aerospace manufacturing. TCE levels in some areas of Suffolk County have been detected at 18 times above health guidelines set by the Environmental Working Group. The former Grumman Bethpage facility is one of the most significant sources, with contamination plumes extending miles from the original site.

Tetrachloroethylene (PCE): The primary solvent used in dry cleaning operations. PCE persists in groundwater for decades after dry cleaning operations cease, and Long Island's dense history of dry cleaners has left widespread low-level PCE contamination throughout Nassau and Suffolk Counties.

Health risks: Both TCE and PCE are classified as human carcinogens. Long-term exposure through drinking water has been linked to kidney cancer, non-Hodgkin lymphoma, and neurological effects.

Nitrates

Nitrates are among the most common groundwater contaminants on Long Island, entering the aquifer from fertilizers, septic systems, and agricultural runoff. Elevated nitrate levels are particularly dangerous for infants under six months old, potentially causing "blue baby syndrome" — a condition that reduces the blood's ability to carry oxygen. The EPA's maximum contaminant level for nitrates in drinking water is 10 milligrams per liter (mg/L).

Suffolk County's agricultural history and the widespread use of lawn fertilizers across Nassau and Suffolk make nitrate testing essential for any private well on the island.

Arsenic

Arsenic occurs naturally in Long Island's geology and can leach into groundwater, particularly in deeper wells. While naturally occurring arsenic is distinct from industrial contamination, the health risks are the same — long-term arsenic exposure is linked to skin, lung, and bladder cancers, as well as cardiovascular and developmental effects. The EPA's maximum contaminant level for arsenic is 10 parts per billion (ppb).

Coliform Bacteria

Bacterial contamination is the most immediately dangerous well water issue, capable of causing acute gastrointestinal illness and, in severe cases, life-threatening infections. Sources include failing septic systems, surface runoff following heavy rain events, and deteriorating well casings that allow surface water to enter the well column. New York State DOH recommends testing private wells for bacteria at least once per year.

How to Know If Your Well Water Is Safe

The only way to know what's in your well water is to test it. Visual inspection and taste mean nothing — the contaminants most likely to harm you on Long Island are colorless, odorless, and tasteless at the concentrations typically found in groundwater.

What to Test For on Long Island

For private well owners on Long Island, a comprehensive water testing panel should include at minimum:

Annual testing (every year):

• Total coliform bacteria and E. coli

Every 3–5 years (or immediately if you've never tested):

• Nitrates and nitrites

• pH and general water chemistry

• Volatile organic compounds (VOCs) — including TCE and PCE

• Heavy metals (arsenic, lead, manganese)

• Sodium

At least once — and immediately if you're in a known impact area:

• PFAS (PFOA, PFOS, and the additional four compounds covered by EPA's 2024 rule)

• 1,4-Dioxane

• Radon in water

New York State's Private Well Testing Act (PWTA) requires water testing for specific parameters whenever a property with a private well is sold. If you've recently purchased a home with a private well, confirm that PWTA testing was completed and review the results.

Who Should Test Immediately

Even if you've tested before, consider immediate retesting if any of the following apply:

• Your property is near a former industrial site, military base, airport, or dry cleaner

• You live in areas of western Suffolk or Nassau County with documented contamination history (Bethpage, Calverton, Islip, Babylon, Hempstead, Levittown)

• You've never specifically tested for PFAS or 1,4-dioxane

• Your well is shallow (drawing from the Upper Glacial aquifer) — these are most vulnerable to surface contamination

• You notice changes in water color, odor, or taste

• A neighbor has reported contamination

• Your property has or had an underground oil tank

How to Get Your Well Water Tested on Long Island

Testing must be conducted by a laboratory certified by the NYSDOH Environmental Laboratory Approval Program (ELAP) for drinking water analysis. Certified labs can be found through the NYSDOH website. The Suffolk County Department of Health Services also offers testing assistance for private well owners.

For the most comprehensive and locally relevant testing, work with an environmental professional who understands Long Island's specific contamination profile and can recommend the appropriate testing panel for your location and well characteristics.

Eastern Environmental Solutions provides professional groundwater sampling and environmental testing services throughout Nassau and Suffolk Counties, drawing on our expertise in soil and groundwater assessment, Geoprobe® drilling, and environmental remediation.

What to Do If Your Well Water Tests Positive for Contamination

Discovering contamination in your well is alarming — but it doesn't necessarily mean your home is unlivable or unsaleable. Here's what to do:

Step 1 — Stop using the water for drinking and cooking immediately Switch to bottled water for all consumption and food preparation until the situation is assessed and addressed. Do not assume boiling will help — boiling kills bacteria but does not remove chemicals like PFAS, 1,4-dioxane, VOCs, or nitrates.

Step 2 — Confirm the results with a second sample A single positive test result should be confirmed with a second sample before taking major action. Collection errors can produce false positives, particularly for bacteria.

Step 3 — Identify the source Understanding where the contamination is coming from helps determine the appropriate response. An environmental professional can help assess whether the source is on your property (a failing septic system, buried oil tank, or surface contamination) or whether your well is drawing in contamination from an off-site source (an industrial plume, neighboring property, etc.).

Step 4 — Evaluate your options

Depending on the contaminant and its concentration, options may include:

• Point-of-use filtration: Reverse osmosis systems are effective against many contaminants including PFAS, nitrates, arsenic, and some VOCs. Note that standard activated carbon filters are not effective against 1,4-dioxane or PFAS.

• Whole-house treatment systems: More comprehensive but significantly more expensive.

• Well deepening or replacement: If contamination is localized to shallow groundwater, drilling a deeper well targeting a different aquifer may access cleaner water.

• Connection to municipal water: Where available, connecting to a regulated public water supply eliminates the ongoing responsibility of private well management.

• Remediation: If contamination originates on your property from a source like an oil tank or historic chemical use, professional remediation of the source and affected soil/groundwater may be required.

Step 5 — Contact your county health department The Nassau or Suffolk County Department of Health can provide guidance, may conduct follow-up testing, and can connect you with assistance programs if contamination is traced to an off-site source.

Eastern Environmental Solutions: Your Partner for Groundwater Safety on Long Island

Eastern Environmental Solutions has spent over 21 years protecting Long Island's homes, businesses, and environment from groundwater contamination. Our groundwater testing and remediation services are built on the same capabilities that make us the region's leading environmental contractor:

What we offer:

• Professional groundwater sampling using our Geoprobe® fleet — the largest in the region

• Soil and groundwater sampling for PFAS, VOCs, 1,4-dioxane, heavy metals, and more

• Phase I and Phase II Environmental Site Assessments

• Environmental remediation and site cleanup

• Oil tank removal and petroleum spill remediation

• 24/7 emergency response

If you have concerns about your well water — whether you're a homeowner, buyer, seller, or commercial property owner — Eastern Environmental Solutions can provide the environmental expertise to assess, test, and address the problem. We don't just identify the issue. We help you resolve it.

📞 Call Eastern Environmental Solutions at (631) 727-2700 for a consultation about your well water or groundwater concerns. Available 24/7. Or request a free quote online.

Frequently Asked Questions: Well Water Safety on Long Island

How do I know if my area has known PFAS or 1,4-dioxane contamination? The Citizens Campaign for the Environment has published interactive maps showing PFAS contamination levels by community across Long Island. The NYSDEC DECinfo Locator also shows data from water well completion reports and environmental monitoring. For the most current and property-specific assessment, contact an environmental professional.

My water tastes and looks fine — do I still need to test? Yes, absolutely. PFAS, 1,4-dioxane, VOCs, nitrates, and arsenic are all colorless and tasteless at the concentrations typically found in Long Island groundwater. The absence of visible signs is not a reliable indicator of safety.

How much does well water testing cost on Long Island? A basic bacteria and nitrate test typically costs $50–$150 through a certified lab. A comprehensive panel including VOCs, heavy metals, and PFAS can range from $300–$800 or more depending on the number of parameters tested. Specific 1,4-dioxane testing costs approximately $250–$300 per sample at certified labs. Contact your county health department — they may offer testing programs or subsidized rates for private well owners.

Does New York State's Private Well Testing Act (PWTA) protect me? The PWTA requires specific water testing at the time of property sale. However, it does not cover PFAS or 1,4-dioxane in its standard required panel. Buyers and sellers of Long Island homes with private wells should negotiate for expanded testing that specifically includes these contaminants.

Is there financial assistance available if my well is contaminated? New York State has established programs to assist private well owners in certain contamination situations. The NYSDOH Private Well PFAS Testing and Mitigation Rebate Pilot Program offers assistance for eligible homeowners. Contact the Suffolk County Department of Health Services or NYSDOH for current program details and eligibility.

Can I install a home filter to remove PFAS and 1,4-dioxane? Reverse osmosis (RO) systems are effective against PFAS at the point of use (e.g., kitchen sink). However, standard RO and activated carbon filters have limited effectiveness against 1,4-dioxane, which requires more advanced treatment. Consult with a water treatment specialist and always test after installation to confirm the system is performing as expected.

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