Per- and polyfluoroalkyl substances (PFAS) are often described as “forever chemicals” for a reason: once they’re in the environment, they’re extremely hard to get rid of. Unfortunately, that also applies to our drinking water. So when people ask, “What’s the best way to remove PFAS from my tap?”, they’re really asking a more complex question:
Which technologies actually work, for which PFAS, in which conditions, and at what cost?
In this article, we’ll unpack what the evidence shows, how experts approach the problem, and what that means for you at the tap – whether you’re a homeowner, facility manager, or simply trying to understand your exposure risk.
Why PFAS are so difficult to remove from water
To understand why not every filter on the shelf is up to the job, it helps to know what makes PFAS unusual:
- They are extremely persistent. The carbon–fluorine bond is one of the strongest in organic chemistry, which is why PFAS don’t readily break down in the environment or in conventional treatment plants.
- They’re highly mobile. Many PFAS are soluble and travel long distances in groundwater and rivers, making them hard to contain once released.
- They come in many forms. There are thousands of PFAS, from “long-chain” compounds like PFOA and PFOS to newer “short-chain” variants and precursors that can transform into other PFAS.
- They occur at very low (but still relevant) levels. Health advisory levels for some PFAS are now in the parts-per-trillion (ppt) range. That’s equivalent to a few drops in an Olympic-sized swimming pool.
Any technology claiming to “remove PFAS” has to be effective at these tiny concentrations, ideally across a range of PFAS types, and remain reliable over time. That narrows the field quite a bit.
The three leading technologies for PFAS removal
Across peer-reviewed studies and water industry practice, three technologies consistently stand out for PFAS removal from drinking water:
- Granular activated carbon (GAC)
- Reverse osmosis (RO)
- Anion exchange resins (AIX)
Each works differently, with distinct strengths and weaknesses. The “best” option depends on your water chemistry, the PFAS mix present, your budget, and whether you are treating water for a household or a whole community.
Granular activated carbon: the current workhorse
Granular activated carbon systems are among the most widely deployed tools for PFAS at both municipal and household level. They work mainly by adsorption: PFAS molecules are attracted to and held on the surface of porous carbon granules.
What it does well
- Effective for many long-chain PFAS. Compounds like PFOS and PFOA are removed at high rates, especially at the start of a filter’s life. Removal efficiencies of >90% are common in lab and field conditions for these compounds when systems are properly designed and maintained.
- Scalable. GAC is already used in many municipal plants for taste, odour, and organic contaminant control, so adding PFAS as a design target is often feasible.
- Accessible at home. NSF-certified countertop and under-sink carbon filters marketed for PFAS can significantly reduce certain PFAS when cartridges are replaced on schedule.
Limitations to be aware of
- Performance drops as the carbon “fills up”. GAC has a finite capacity. Once the pores are saturated with PFAS and other organics, removal efficiency drops and “breakthrough” occurs – PFAS begin to pass through unremoved.
- Less effective for many short-chain PFAS. Shorter-chain molecules are more mobile and less strongly adsorbed to carbon. Several studies show faster breakthrough and lower removal rates for short-chain PFAS compared to long-chain compounds.
- Water quality matters. High levels of natural organic matter, certain competing contaminants, or elevated temperatures can all reduce performance and shorten the effective life of the carbon bed.
- Requires regeneration or disposal. Spent carbon contains concentrated PFAS and must be managed as a contaminated waste, either by high-temperature incineration or emerging alternative destruction technologies.
Where GAC makes sense
- Municipal systems already using or able to adopt carbon in large contactors, particularly where long-chain PFAS dominate.
- Household point-of-use filters (under-sink or countertop) with verified PFAS reduction performance, as a first-line barrier for known contamination.
- As a polishing step after other treatments, to catch residual PFAS and a broad range of organic contaminants.
GAC is often the first technology utilities consider because it is familiar, relatively cost-effective at scale, and proven for several of the best-studied PFAS. But as regulatory limits tighten and short-chain PFAS gain attention, it is rarely sufficient on its own in the long term.
Reverse osmosis: high removal, higher complexity
Reverse osmosis operates very differently from carbon. Instead of adsorbing contaminants, it uses a semi-permeable membrane that allows water molecules to pass while rejecting many dissolved ions and organic molecules, including PFAS.
What it does well
- High removal efficiency across PFAS types. Under well-designed conditions, RO systems can remove more than 90–99% of many PFAS, including problematic short-chain compounds that slip past carbon.
- Effective for multiple contaminants. RO can simultaneously reduce PFAS, nitrates, some heavy metals, hardness, and many other dissolved substances. This makes it attractive where water quality issues are complex.
- Point-of-use systems are widely available. Under-sink RO units are already in common use for desalination or taste improvement and can be selected for PFAS reduction.
Limitations and trade-offs
- Water wastage. Traditional RO systems produce a concentrated waste stream (“reject water”). Depending on design, 2–4 litres may be rejected for every litre of purified water produced, though modern systems can be more efficient.
- Energy and pressure requirements. RO membranes need sufficient pressure, and larger or centralised systems consume more energy than GAC-based adsorption.
- Removes beneficial minerals. Because RO strips many dissolved ions, treated water can taste “flat” and lack calcium, magnesium, and other minerals. Some systems include remineralisation stages to address this.
- Membrane fouling. Water with high levels of particulates, hardness, or organic matter can foul membranes, requiring pre-treatment and regular maintenance.
- Waste management. The reject stream contains a concentrated PFAS mixture and must not simply be discharged where it can re-enter the environment untreated.
Where RO makes sense
- Household point-of-use treatment where PFAS levels are elevated and a high-performance barrier is desired for drinking and cooking water.
- Facilities with high health sensitivity such as hospitals, laboratories, and food-production sites needing consistent, low-contaminant water.
- Settings with multiple contaminants where PFAS are one of several chemical concerns best addressed by a broad-spectrum treatment.
If your priority is maximum PFAS reduction at the tap, an under-sink RO system combined with a high-quality carbon pre-filter is often one of the most effective household solutions currently available.
Anion exchange resins: targeted PFAS capture
Anion exchange (AIX) resins are synthetic beads with positive charges on their surfaces. Many PFAS exist as negatively charged ions in water, so they are attracted to and captured by these resins through ion exchange and other interactions.
What it does well
- High affinity for many PFAS. Tailored AIX resins can achieve excellent removal of both long- and some short-chain PFAS under the right conditions.
- Longer bed life than GAC in some cases. For certain PFAS mixtures and water qualities, AIX can reach higher loading before breakthrough, meaning fewer changeouts.
- Compact footprint. Resin systems can be physically smaller than equivalent GAC units for a similar performance level, which is advantageous in space-limited plants.
Limitations and challenges
- Resin selection is critical. Not all resins perform equally for PFAS; some are optimised for other anions like nitrates. Choosing a resin designed and validated for PFAS is essential.
- Competing anions can interfere. High concentrations of sulfate, bicarbonate, or other anions in the water can compete with PFAS for resin sites, reducing effectiveness.
- Spent resin is a concentrated PFAS waste. As with GAC, treatment or safe disposal is required, and regeneration processes must avoid releasing PFAS back into the environment.
- Less common at household scale. While resin-based cartridges exist, integrated PFAS-specific AIX systems are more often seen in municipal or industrial applications.
Where AIX makes sense
- Municipal and regional treatment works facing mixed PFAS contamination, often in combination with GAC or other polishing steps.
- Industrial sites managing PFAS-laden process water or remediation systems, where compact and high-capacity units are needed.
Ion exchange is best thought of as a precision tool: highly effective in the right hands, but dependent on good design, accurate water quality data, and responsible waste management.
So, which technology is “best” for PFAS removal?
There is no single universal winner. Instead, experts tend to converge on a layered approach:
- For households: A point-of-use reverse osmosis system, ideally combined with a high-quality activated carbon stage, offers some of the most robust PFAS reductions currently available for drinking and cooking water. For those who prefer not to use RO, a NSF-certified activated carbon filter specifically tested for PFAS can still provide meaningful reduction, especially for long-chain PFAS – but it must be maintained rigorously.
- For community and municipal systems: A combination of GAC and ion exchange, often supported by upstream process optimisation and potential membrane technologies, provides a more resilient barrier across a range of PFAS and changing water qualities.
From a public health perspective, the most sustainable long-term “best way” is of course to prevent PFAS from entering water sources in the first place. But for communities already affected, practical solutions at the treatment plant and at the tap are essential.
How to evaluate a home filter for PFAS
Not every product that mentions PFAS in its marketing lives up to the promise. When assessing household filters, a few critical checks will help separate robust solutions from wishful thinking.
Look for independent certification
- In many markets, NSF/ANSI standards are the benchmark. While a dedicated PFAS reduction standard is emerging, reputable manufacturers will publish test data for key PFAS (such as PFOA and PFOS) at defined challenge concentrations.
- Check that testing conditions reflect realistic use: flow rates, water temperature, and contaminant loads similar to real-world conditions rather than idealised laboratory setups.
Read the performance data, not just the claims
- Look for percentage reduction figures and initial contaminant concentrations.
- Check whether performance is reported over the full cartridge life or only at the beginning. PFAS removal often declines over time.
- See which specific PFAS the device has been tested against. A filter tested only for PFOA and PFOS may behave differently with other PFAS in your water.
Be realistic about whole-house vs point-of-use
- Whole-house systems (point-of-entry) treat all water entering the home, which is helpful for bathing and laundry exposure reduction but often significantly more expensive and complex when designed to remove PFAS reliably.
- Point-of-use systems (e.g., an under-sink RO or carbon filter) focus on water used for drinking and cooking, the main ingestion routes. This is typically the most cost-effective starting point.
Maintenance is non-negotiable
- PFAS filters that are not replaced on time can become ineffective or even start releasing contaminants previously captured.
- If you are unlikely to follow a strict maintenance schedule, a technologically perfect system on paper will not deliver its theoretical benefits in practice.
The role of water testing in choosing the right solution
You cannot choose an optimal treatment strategy if you do not know which PFAS are present and at what levels. Unfortunately, PFAS testing is more complex and expensive than standard water tests.
What to consider for testing
- Scope of analysis. Does the laboratory test for a broad suite of PFAS (including short-chain species), or just a few legacy compounds?
- Detection limits. Are the laboratory’s reporting limits low enough to detect PFAS at current and emerging regulatory thresholds?
- Sampling protocol. PFAS can be introduced from sampling equipment, storage containers, or even waterproof clothing. Laboratories should provide clear instructions to avoid contamination.
When testing is particularly valuable
- If you live near known PFAS sources, such as firefighting training sites, industrial facilities, airports, or landfills.
- If your local authority or water supplier has reported PFAS detections in nearby supplies but not yet implemented treatment upgrades.
- When you are considering a substantial investment in a whole-house filtration system and need to match technology to contaminants.
For many households, a practical path is to rely first on publicly available water quality reports and regulatory monitoring, then consider targeted testing if risk factors or uncertainties remain.
Emerging technologies: what is coming next?
GAC, RO, and ion exchange are the current mainstays, but research is advancing quickly. Several emerging approaches aim not only to capture PFAS, but to destroy them permanently.
Some promising directions include:
- Advanced oxidation and reduction processes. Techniques using UV light, electrochemical cells, or powerful oxidants to break PFAS molecules apart. So far, most are energy-intensive and better suited to concentrated waste streams than dilute drinking water.
- Specialised adsorbents and membranes. Novel sorbents (such as tailored ion-exchange materials, modified clays, or carbon-based nanomaterials) show enhanced affinity for short-chain PFAS in lab tests. Real-world scale-up and safety assessment are ongoing.
- Plasma-based destruction. Non-thermal plasma technologies are being tested to degrade PFAS in concentrated wastes, for example from spent GAC or ion exchange regenerants.
While these technologies are not yet ready to replace established methods at the tap, they are crucial for closing the loop: capturing PFAS is only half the job if we later release them back into the environment.
Putting it all together: practical strategies for lower-PFAS drinking water
If you are trying to reduce PFAS in your drinking water today, a structured approach helps:
- Check your local information first. Review water supplier reports, local authority statements, and any publicly available PFAS monitoring results. In some areas, proactive treatment is already in place.
- Identify your priorities. Are you focusing on water for drinking and food preparation, or do you also want to reduce exposure during bathing and showering? Your answer will shape whether you prioritise point-of-use or whole-house systems.
- Choose technologies with evidence, not just promises. Favour RO and high-quality activated carbon or resin-based systems with independent test data for PFAS, clear maintenance requirements, and transparent documentation.
- Plan for maintenance and lifespan. Consider filter replacement costs, ease of servicing, and how reliably you can follow manufacturer schedules. A modest system that you manage well can outperform a sophisticated one that is neglected.
- Stay informed. Regulations for PFAS are tightening, monitoring is improving, and utilities are upgrading treatment. What you need today may change as centralised treatment improves and as new technologies mature.
Removing PFAS from drinking water is technically challenging, but it is not impossible. With a clear understanding of how each technology works, what the data show, and how to apply that knowledge in a practical way, you can make informed choices that significantly reduce your exposure while broader regulatory and industrial changes catch up.