Military Base PFAS: How AFFF Firefighting Foam Reaches Your Water

Firefighting foam used at more than 700 U.S. military bases created plumes of PFAS in groundwater. These forever chemicals migrate from runways and training areas into nearby wells and public supplies, sometimes miles from the fence line.

What Is AFFF, and Why Did the Military Use It?

AFFF, aqueous film-forming foam, is a firefighting agent the U.S. military has used since the 1960s to smother jet-fuel fires. It works so well because it contains PFAS, including PFOA and PFOS. The Department of Defense has identified more than 700 installations with known or suspected PFAS contamination (U.S. DoD PFAS report to Congress, 2023).

The chemistry that made AFFF effective is the same chemistry that makes it a lasting problem. PFAS molecules are built around carbon-fluorine bonds, among the strongest in organic chemistry. That bond lets the foam spread a thin, fuel-sealing film across burning liquid. It also means the compounds resist heat, water, and natural breakdown, which is why people call them "forever chemicals."

Bases used AFFF in two ways: fighting real fires and, far more often, routine training drills. For decades, crews sprayed foam onto practice pads and let it run off into soil and drains. Nobody was capturing it. That repeated, low-drama training use, not a single dramatic accident, is what seeded most base plumes.

How Does Firefighting Foam Turn Into a Groundwater Plume?

A PFAS plume forms when foam residue soaks through soil and reaches the water table, then spreads along with groundwater flow. Because PFAS are highly soluble and do not degrade, a plume keeps moving outward for years. The ATSDR describes PFAS as persistent and mobile, capable of migrating well beyond the original source (ATSDR Toxicological Profile for Perfluoroalkyls, 2021).

Here is the sequence. Foam is applied at the surface. Rain and time carry the dissolved PFAS downward through soil. Once the chemicals hit groundwater, they travel in whatever direction the aquifer flows, sometimes toward a drinking-water well, sometimes toward a stream that feeds a public intake. The plume is not a puddle under the runway. It is a slow, invisible current.

This is the part homeowners underestimate. A base can be a mile away and still sit upgradient of your well, meaning groundwater flows from the base toward your property. In our review of published military-site investigations, the wells that test positive are frequently off-base, which is exactly why regulators test neighborhoods, not just the installation.

Legal vs. Safe: What Do EPA's PFAS Limits Actually Mean?

EPA finalized its first enforceable PFAS drinking-water limits in April 2024, setting PFOA and PFOS at 4 parts per trillion each. The important nuance is that EPA set the health-based goal for both compounds at zero, because they are treated as likely carcinogens with no proven safe level (EPA PFAS National Primary Drinking Water Regulation, 2024).

Read the first two rows carefully. For PFOA and PFOS, the enforceable 4 ppt limit is not a safety line. It reflects the lowest level laboratories can reliably measure and utilities can feasibly treat. EPA's actual health target is zero. So water that "passes" at 3 ppt still carries measurable forever chemicals, and lower is always better.

For adults, independent health-based screening values land in a similar zone: about 7 ppt for PFOS and roughly 14 ppt for PFOA, both above the 4 ppt legal limit. The stricter numbers appear for infants, pregnant women, and the elderly, whose bodies clear PFAS more slowly. That pattern is why the honest headline is "no safe level," not a tidy multiplier.

One more honesty point. AFFF also breaks down into newer compounds like 6:2 fluorotelomer sulfonate that show up in base water. These emerging PFAS have no federal drinking-water limit yet and are only tracked under EPA's monitoring rule, so we will not invent a safe number for them. What we can say is simple: if AFFF was used nearby, test for the full PFAS panel, not just the five regulated compounds.

What Is the Military Doing to Clean It Up?

The Department of Defense has acknowledged the contamination and is investigating and remediating sites, but cleanup will take years. In 2024, EPA designated PFOA and PFOS as hazardous substances under the Superfund law, which strengthens the legal tools to hold polluters accountable and fund cleanups (EPA CERCLA PFAS designation, 2024).

Two changes matter for the future. First, Congress directed the military to stop using PFAS-based AFFF and switch to fluorine-free foam, with the transition targeted for October 2024. Second, EPA's hazardous-substance designation means the government can require responsible parties, including federal agencies, to investigate and pay for cleanup at contaminated sites.

None of that helps the water flowing through your tap today. Investigations move installation by installation, and treating an aquifer is slow, expensive work. In 2025, EPA also said it would keep the 4 ppt PFOA and PFOS limits while extending utility compliance deadlines to 2031 and reconsidering the limits for the other compounds. Translation: the rules exist, but full protection is years out. Your well or utility is serving water right now.

What Can You Do If You Live Near a Base?

Test your water for PFAS first, then match treatment to what you find. Standard municipal processes like chlorination, aeration, and sand filtration do not remove PFAS, because nothing about them breaks a carbon-fluorine bond. According to NSF International, reverse osmosis certified to NSF/ANSI 58 removes PFAS effectively, typically more than 90% (NSF PFAS filtration guidance).

Three treatment options actually work against PFAS:

1. Reverse osmosis (RO). The most complete point-of-use option for a broad PFAS range, including short-chain compounds. An under-sink RO unit protects drinking and cooking water. Look for NSF/ANSI 58 certification for PFAS reduction.
2. Granular activated carbon (GAC). Effective when correctly sized, but short-chain PFAS can break through sooner, so replacement schedules matter. Choose a filter certified to NSF/ANSI 53 for PFOA and PFOS.
3. Ion-exchange resin. Specialized anion-exchange resins capture PFAS well and suit whole-house use, though they need professional installation and maintenance.

The report is the free part. Enter your address to see what has been measured in your area, then decide whether you need treatment at all. A water test through a certified lab is the paid step, and it is worth it near a base with a known AFFF history.

For the Connecticut example of exactly this pattern, including a Navy base listed as a Superfund site with PFAS in nearby private wells, see our detailed local investigation of PFAS around the Groton and New London submarine base.

Keep Reading

• Navy PFAS in Groton: decades of contamination and what nearby well owners should do
• The connection between your water, your thyroid, and your hair
• Why your water bill is rising to pay for PFAS cleanup

Sources: U.S. EPA, PFAS National Primary Drinking Water Regulation, 2024; U.S. EPA, CERCLA hazardous substance designation for PFOA and PFOS, 2024; U.S. Department of Defense, PFAS report to Congress on installation assessments, 2023; Agency for Toxic Substances and Disease Registry (ATSDR), Toxicological Profile for Perfluoroalkyls, 2021; NRDC PFOS health-based value (ATSDR MRL basis), 2019; New Jersey Department of Environmental Protection PFOA health-based value, 2017; Environmental Working Group Tap Water Database; NSF International PFAS filtration guidance. Adult health-based values (about 7 ppt PFOS, 14 ppt PFOA) are independent screening levels, not EPA enforceable limits. EPA's health-based goal for PFOA and PFOS is zero. Test your water and consult a certified lab.