PFAS and Immersion Cooling: What Data Center Operators Need to Know
Most two-phase immersion fluids are fluorinated. Regulation and supply are changing – what this means for existing and new projects.
Updated 9 November 2026 · Published by IsoTec
What are PFAS?
PFAS (per- and polyfluoroalkyl substances) are a large group of fluorinated chemicals. Under the OECD definition of 2021, PFAS are fluorinated substances that contain at least one fully fluorinated methyl or methylene carbon atom. Many PFAS are extremely persistent in the environment, which is why they are called “forever chemicals”.
Which immersion fluids are affected?
Fluids for two-phase immersion – fluorocarbons, hydrofluoroethers and fluoroketones – fall under PFAS definitions in most cases. The same applies to fluorinated single-phase fluids. Hydrocarbons and esters used in single-phase systems are not fluorinated chemistries.
3M exit from PFAS production
In December 2022, 3M announced that it would exit PFAS manufacturing and work to discontinue the use of PFAS across its product portfolio by the end of 2025. This includes fluid families widely used in two-phase cooling and electronics. Other manufacturers continue to supply fluorinated fluids, but operators have to plan for supply, price and regulatory risk.
The EU universal PFAS restriction
- 2023: Denmark, Germany, the Netherlands, Norway and Sweden submitted a proposal to restrict PFAS as a group under REACH; ECHA published it in February 2023.
- March 2026: ECHA’s Committee for Risk Assessment (RAC) adopted its opinion and supported a broad restriction.
- 2026: the Committee for Socio-economic Analysis (SEAC) consulted on its draft opinion until 25 May 2026; its final opinion is expected by the end of 2026.
- Next: the European Commission prepares the legal act, which is then examined by the REACH Committee, the European Parliament and the Council.
Which uses will get transition periods or exemptions is not yet decided. Follow the official ECHA information.
What it means for operators
- Existing two-phase systems: secure fluid supply for top-ups, minimise vapour losses, plan collection and proper disposal of used fluid.
- New projects: single-phase immersion with hydrocarbons or esters, or direct-to-chip cooling, avoids dependence on fluorinated fluids.
- Corporate policies: many companies have internal targets to phase out PFAS in their supply chains.
Switching from two-phase to single-phase
The two principles transfer heat differently, so a fluid cannot simply be replaced in an existing tank. Switching means a new tank or CDU design, adapted heat sinks and a new compatibility qualification. See single-phase vs two-phase immersion cooling.
Ester fluids as an alternative
Esters are not fluorinated. They combine high flash and fire points, high moisture tolerance and good heat transfer for single-phase systems. IsoTec ester fluids are based on non-fluorinated ester chemistry. See immersion cooling fluids compared and the data center immersion cooling guide.
Frequently asked questions
Are immersion cooling fluids PFAS?
Most fluorinated two-phase fluids are PFAS. Hydrocarbon and ester fluids used in single-phase immersion are not fluorinated.
Will two-phase immersion fluids be banned in the EU?
The universal PFAS restriction is still in the decision process. RAC supported a broad restriction in March 2026; SEAC’s final opinion is expected by the end of 2026. Exemptions and transition periods are not yet decided.
Can I replace a two-phase fluid with an ester?
Not in the same tank. Esters are single-phase fluids; the system has to be designed for single-phase operation.
Moving away from fluorinated fluids?
We help you evaluate ester fluids for single-phase immersion. IsoTec products are supplied to customers outside Germany.