For sixty years, the foam that put out fuel fires at sea worked because of a chemistry that will not break down in the environment. That same persistence is why it is now being forced off ships, and why swapping it out is far more complicated than emptying a tank and refilling it.
Why AFFF Is Being Forced Off Ships
Aqueous Film Forming Foam, universally known as AFFF, has been the shipboard weapon of choice against fuel fires since the 1960s. It works brilliantly. Mixed with water and air, it spreads a thin film across a burning hydrocarbon surface, sealing off the vapours and smothering the fire faster than almost anything else. On a vessel carrying fuel, cargo oil, and machinery spaces, that speed and reliability made it close to irreplaceable.
The problem is what gives AFFF its power. The film-forming ability comes from PFAS, per- and polyfluoroalkyl substances, a family of synthetic compounds nicknamed forever chemicals because they do not meaningfully break down in the environment. They accumulate in water, soil, and living tissue, and a growing body of research has linked some of them to serious health effects. PFOS, one specific member of that family, was the key ingredient in traditional AFFF.
Regulators have been closing in for years. PFOS was listed under the Stockholm Convention on Persistent Organic Pollutants back in 2009, restricting its production and use across more than a hundred countries. The maritime-specific rules simply took time to catch up. Now they have.
What the IMO Rule Actually Says
The International Maritime Organization finalised its shipboard prohibition in 2022 and gave it force through SOLAS regulation II-2/10.11. In essence, it bans firefighting media containing PFOS from ships. The timing depends on the vessel. A new ship, with its keel laid on or after 1 January 2026, must comply from delivery. An existing ship must comply by its first applicable survey on or after 1 January 2026. For most of the world fleet, in other words, the deadline is not a distant date. It arrives at the next survey.
One nuance matters for anyone reading the fine print. The IMO rule targets PFOS specifically, and it sets an allowable trace limit rather than demanding absolute zero. Foams with PFOS content below roughly 10 parts per million can still satisfy the IMO requirement, which means a high-purity, low-PFOS C6 fluorinated foam can technically comply, as can a fully fluorine-free foam. That distinction sounds like flexibility, but as the next section shows, it collides with a stricter regime.
New ships: Keel laid on or after 1 January 2026. Must use a PFOS-free foam from delivery, whether a compliant low-PFOS C6 foam or a fluorine-free foam.
Existing ships: Keel laid before 1 January 2026. Must comply by the first applicable survey on or after 1 January 2026.
The test: No PFOS above the allowable trace limit in fixed systems or portable equipment.
The scope: Applies globally to SOLAS ships, so it is the one rule every internationally trading vessel must meet.
The EU Rule That Bites Harder
The IMO ban is the global floor. In European waters, a tougher rule sits on top of it. The EU’s PFAS restriction, published in October 2025, does not single out PFOS. It targets all PFAS-containing foams. The practical trigger for shipping is sharp: from 23 October 2025, new PFAS-containing firefighting foam can no longer be brought aboard civil vessels in EU ports.
The IMO rule lets a low-PFOS C6 foam comply. The EU rule does not. A foam that satisfies one regime can be barred under the other, and a ship trading into Europe has to meet the stricter of the two.
There is a grace period. Existing PFAS foam already on board can, in principle, continue in use for a number of years, with longer transition windows for higher-risk maritime and offshore uses than for land-based ones. But the bring-aboard cutoff is what changes behaviour now. An operator cannot top up or replace fluorinated foam from a European port, which for an internationally trading vessel effectively forces the switch well ahead of the longer phase-out dates. Add the fragmented picture elsewhere, where the United States and others have their own evolving and sometimes conflicting rules, and a ship trading globally faces a patchwork it can only navigate by moving to a foam that satisfies the strictest regime it will encounter.
The Supply Problem Nobody Budgeted For
Regulation is only half the pressure. The market has already moved. Because land-based use makes up the large majority of the firefighting foam market, and those users faced their own deadlines, mainstream production has shifted decisively to fluorine-free foam since 2024. The commercial consequence is blunt. An operator who waits until the last moment to replace condemned foam, or simply to top up a fluorinated system, may find the product is no longer being made in the quantity they need.
Without compliant firefighting foam on board, a ship cannot sail. The regulation and the shrinking supply of old foam are pushing in the same direction, and waiting is the one option that does not work.
This reframes the deadline as a logistics problem as much as a compliance one. A vessel that cannot demonstrate compliant firefighting capability is not seaworthy, and Port State Control in stricter jurisdictions is expected to enforce the foam rules firmly. Between the regulation and the supply squeeze, the safe assumption is that the transition needs to be planned now, not deferred to the last permitted survey.
Fluorine-Free Foam Is Not a Drop-In Swap
The most expensive mistake an operator can make is to treat this as a like-for-like refill. Fluorine-free foam, often labelled F3, does not work the same way as AFFF. It does not form the thin sealing film that gave the old foam its speed. Instead it builds a thicker physical blanket over the fuel, which has to stay intact under the heat, vibration, and movement of a live fire on a moving ship. It also tends to be more viscous than the foam it replaces. Those differences ripple through the whole system.
The Contamination Trap
Here is the trap that catches operators who do treat it as a simple refill. Forever chemicals are forever inside the system too. PFAS residue clings to the tanks, pipework, and proportioners of a system that has run AFFF for years. Pump fresh fluorine-free foam into an uncleaned system, and it picks up enough residual PFAS to fail a test, leaving a vessel that believes it is compliant but is not.
Test first: Analyse the existing foam and system for PFOS and wider PFAS, using laboratory methods sensitive enough to find hidden precursors, not just a spot check.
Clean, do not just drain: Thoroughly clean and flush tanks and pipework, since residual PFAS can contaminate the new foam and undermine compliance.
Verify after refilling: Re-test to confirm the cleaned system and new foam are genuinely below the limits that apply.
Dispose responsibly: Condemned fluorinated foam is a hazardous waste and must be disposed of through proper channels, not discharged.
The scale of the contamination legacy is not theoretical. Cleaning up land sites where fluorinated foam was used for training has run into billions, which is a useful reminder that this chemistry does not simply rinse away. On a ship, the same principle applies at a smaller scale: the residue has to be actively removed, not assumed gone.
What a Clean Transition Looks Like
Pulled together, the sensible path is straightforward even if the detail is technical. Audit what foam is currently aboard and confirm which rules the vessel must meet across its trading pattern. Select a marine-certified replacement that satisfies the strictest applicable regime, which for ships trading into Europe means looking beyond the IMO’s PFOS-only threshold. Test the existing system, clean it properly rather than just draining it, refill with the compatible new foam, and verify the result by testing again. Then update the documentation, the IHM, and the safety management system to reflect the change.
Done deliberately and early, the switch is a manageable maintenance project. Done in a rush at the final survey, against a shrinking supply of both old and new foam and with a contaminated system, it becomes the reason a ship sits alongside unable to sail. The chemistry that made AFFF so effective is exactly why it takes real care to replace, and the operators who plan the transition rather than react to it are the ones who will keep trading without interruption.
Frequently Asked Questions
What is the difference between PFOS, PFAS, and AFFF?
PFAS is the broad family of per- and polyfluoroalkyl substances, the forever chemicals. PFOS is one specific compound within that family. AFFF, aqueous film forming foam, is the firefighting foam that traditionally relied on these fluorinated chemicals to form its fuel-sealing film. The IMO rule targets PFOS specifically, while the EU rule targets the whole PFAS family, which is why the EU restriction is broader.
Does the IMO ban all fluorinated foam?
No. The IMO prohibition under SOLAS II-2/10.11 targets PFOS and sets an allowable trace limit rather than requiring absolute zero. A high-purity, low-PFOS C6 foam can technically comply with the IMO rule. However, the EU’s broader PFAS restriction does not allow that, so a foam acceptable under the IMO rule may still be barred from being brought aboard in EU ports.
When must an existing ship comply with the IMO rule?
An existing ship, meaning one whose keel was laid before 1 January 2026, must comply by its first applicable survey on or after 1 January 2026. New ships must comply from delivery. Because the trigger for existing ships is the next survey, many vessels reach their deadline at different times through 2026 and beyond, which is why planning ahead matters.
Can I just pour fluorine-free foam into my existing AFFF system?
No. Fluorine-free foam behaves differently, tends to be more viscous, and may need changes to proportioning and discharge equipment. Just as important, PFAS residue in the tanks and pipework can contaminate the new foam and cause it to fail testing. A proper changeover requires testing, thorough cleaning of the system, refilling with a compatible certified foam, and re-testing to confirm compliance.
Why not just keep using my current foam until it runs out?
Two reasons. First, regulation: in EU ports you cannot bring new PFAS foam aboard from late 2025, and the IMO deadline applies at your next survey, so waiting narrows your options. Second, supply: production has shifted to fluorine-free foam, so replacing or topping up old fluorinated foam is becoming difficult. A ship without compliant firefighting foam on board is not seaworthy, so running the old stock down without a plan is a real operational risk.
Sources: gCaptain, Choosing a Shipboard AFFF Replacement (SOLAS II-2/10.11) · MarineLink, Marine Industry Faces 2026 Deadline for Fluorine-Free Foam · SAFETY4SEA / VIKING, foam contingency planning · Star International, fluorine-free foam FAQs (EU rule detail) · IMO SOLAS II-2/10.11; Stockholm Convention on POPs; EU REACH PFAS restriction (2025)