Filtering PFAS: which technique really works?

Reading time: ~11 minutes

What exactly is PFAS filtering?

The word filtering suggests a sieve, and that's exactly where the confusion begins. PFAS molecules are dissolved in the water, just like sugar in tea. A sieve with small holes does nothing about that. You need a material that chemically binds the molecules, or a membrane with pores so small that virtually only water molecules pass through.

That difference also immediately explains why not every water filter is a PFAS filter. A carbon cartridge in a filter jug improves taste, odour and the perception of chlorine, but that's a different achievement to demonstrably lowering a PFAS concentration. If you want to know how filtration works at its core, we explain that step by step in how a water filter works. And if you're not yet clear on what PFAS actually are, start with what PFAS are and why they don't break down.

How much PFAS is in Dutch tap water?

Less than most people think, and the figures are public. For twenty different PFAS, the Netherlands has a statutory permitted level of 100 nanograms per litre, and Dutch tap water meets that, reports the RIVM. That limit applies from 2024, and all drinking water companies must comply by 2026, explains Brabant Water.

In addition, the RIVM has applied a stricter guideline value of 4.4 nanograms per litre since 2022, expressed in PFOA equivalents. That is an advisory value, not a statutory limit, and that distinction is left out of many PFAS reports. Where you live also matters: around sixty per cent of Dutch tap water comes from groundwater, which contains less PFAS than tap water made from surface water.

Another figure that puts the conversation in perspective: people in the Netherlands take in roughly three times as much PFAS through food as through tap water. Through tap water alone, intake stays below the health-based limit value. Through food and tap water combined, intake rises above it, and that is precisely why the RIVM advises lowering total intake. If you want to see what your supplier measures, we've listed that for the largest ones in our piece on the water quality of Vitens.

Why is PFAS so difficult to filter?

Three properties make PFAS the most difficult type of contaminant in the entire filtration world.

The bond is extremely strong. The carbon-fluorine bond is one of the strongest bonds in organic chemistry. As a result, PFAS barely break down in the environment or in a filter. They don't disappear; at most, they are transferred to the filter material.

There are thousands of variants, and they behave differently. Long chains such as PFOA and PFOS bind relatively well to activated carbon. Short and ultra-short chains, of which TFA is the best known, are much smaller and slip through more easily. So a filter tested on PFOA and PFOS says nothing about TFA.

Saturation is invisible. A carbon filter eventually becomes full. You don't taste it, you don't see it, and the water keeps looking the same. That's why the replacement schedule for a PFAS filter isn't a detail but the core of how it works. We go into that in more depth in how often you should replace a water filter.

The three techniques that tackle PFAS

According to NSF International, granular activated carbon, anion-exchange resin and reverse osmosis membranes are currently the most widely used techniques for PFAS removal. They're listed below in the order you'll encounter them at home.

1. Activated carbon, in granular form or as a carbon block

Activated carbon has an enormous internal surface area to which organic molecules stick. That's the same technique drinking water companies use in their own treatment process. It works best on the longer PFAS chains and least on the ultra-short ones, such as TFA.

For home use, activated carbon comes in two forms. Loose granules, where water can flow between the grains without touching all of them. And a compressed carbon block, where the water has to pass through the material, making contact more even. For under-sink filters, the carbon block is the usual choice, because the flow rate there is high.

NSF/ANSI 53 covers exactly these devices: water treatment with activated carbon or anion-exchange resin. Since the 2022 revision, a filter may only carry the Total PFAS claim if the combined level of PFOA, PFOS, PFHpA, PFHxS, PFNA and PFBS stays below 20 nanograms per litre. That's a fifth of the Dutch statutory limit, and immediately the most concrete figure you can use in this field.

2. Ion exchange with anion resin

In water, PFAS carry a negative charge. An anion-exchange resin swaps those charged molecules for harmless ions. The advantage is that the technique also acts on shorter chains, where activated carbon falls short sooner. The disadvantage is that the resin is specific and relatively costly, and in household systems it's almost always combined with carbon rather than used on its own.

3. Reverse osmosis

With reverse osmosis, water is pushed under pressure through a semi-permeable membrane. Whatever is too large is left behind, and that applies to almost the entire PFAS spectrum, including the shorter chains. Reverse osmosis falls under NSF/ANSI 58, with the same limit of 20 nanograms per litre for the Total PFAS claim.

That comes with three practical drawbacks. An osmosis system needs rinse water, so you throw away part of your water. The membrane also blocks calcium, magnesium and potassium, which makes the water taste flat and removes the useful minerals. And the system is larger and needs more maintenance. We've worked out what that means for your health and your taste experience in whether osmosis water is healthy or not and in the technical explanation of an RO water filter.

What doesn't work against PFAS?

• Boiling: PFAS don't evaporate at 100 degrees. Boiling water down actually makes the concentration higher, not lower.
• A sediment or screen filter: that blocks particles, not dissolved molecules.
• An ordinary filter jug without a PFAS claim: a cartridge designed for taste and chlorine hasn't been tested for PFAS. If there's no NSF/ANSI 53 or 58 claim on it, don't assume it happens.
• A water softener: that exchanges calcium and magnesium for sodium. Limescale comes out, PFAS doesn't.
• A boiling water tap or Quooker: that regulates temperature and convenience, not purification. What a Quooker does and doesn't do, and how to fit a filter for it, is on our page about the Quooker water filter.

Comparison: which technique suits which situation?

The table shows why there's no single winner. Reverse osmosis covers the broadest spectrum, but pays for that with minerals and rinse water. Activated carbon leaves the water intact, but has a limit at the shortest chains. Which trade-off suits your household depends on your source, your usage and how much maintenance you'll accept. We lay out that choice systematically on the page where we explain which filtration technique blocks which substances.

What to look out for with a PFAS filter

Ask about the certification, not the brochure

A claim without a standard is just an opinion. Look for NSF/ANSI 53 on carbon and resin filters and for NSF/ANSI 58 on osmosis systems. Both are independently tested and the test method is laid down through an accredited process. For reference: the US drinking water standards from April 2024 set the limit for PFOA and PFOS at 4.0 nanograms per litre and for PFHxS, PFNA and GenX at 10 nanograms per litre, according to NSF. Those figures give you a sense of the scale involved.

Replace it on time, because breakthrough is real

A saturated carbon filter can release previously absorbed substances again. So the replacement moment isn't a maintenance chore but a safety commitment to yourself. Put the date in your diary and stick to it, even if the water still tastes fine.

Watch out for stagnant water

A filter jug sitting on the counter for days is a different situation to a filter in the pipe. Dutch tap water is supplied without chlorine, so once water stands still and reaches room temperature, bacteria can multiply. An inline filter doesn't store water and doesn't have that problem.

Also look at what's removed that you actually need

Calcium and magnesium in tap water contribute to your daily intake. A system that strips everything out also removes those. If you drink one and a half to two litres of water a day, that's not a minor detail. In how much water you need per day, we work out exactly how much that adds up to.

What experts say, and what we think of it

Fair is fair: not everyone thinks a PFAS filter at home is necessary. The RIVM points out that drinking water companies purify the water as well as they can, that the government is working on stricter rules, and that research is under way into better techniques for removing PFAS from water. The amount of PFAS you take in through tap water is, moreover, below the health-based limit value. Anyone looking purely at PFAS and living in a groundwater area doesn't strictly need a filter.

We sell filters, so you're entitled to weigh that when reading this. But it's the honest framework, and it leads to a better decision than a scare figure. At PureFilter, we see that customers rarely come for a single substance. They come because they want to tackle limescale, chlorine taste, lead from old pipes, microplastics and PFAS all at once, and because they're done refilling jugs. That's a convenience and breadth argument, not an alarm argument, and it deserves an honest story.

How PureFilter solves this

The PureFilter Mineral+ is an inline under-sink filter with a multi-stage build that removes more than 100 contaminants, including PFAS, microplastics, heavy metals such as lead and copper, fluoride, nitrate, pharmaceutical residues and chlorine. It is NSF-certified to 42, 53, 61 and 372. It's explicitly not reverse osmosis, so you don't lose any rinse water and the water isn't stripped.

The final step is what sets us apart. Via Swedish Mineral Rock™, magnesium, calcium and potassium are added back to the water after it has been purified. Purify first, then mineralise: that order is the whole point. The result is water that tastes softer and fuller instead of flat.

In practice: the filter sits on the cold water line under your sink and you install it in 5 to 10 minutes without a plumber, using a single water pump pliers. A 3/8 connection is included as standard. You later swap the cartridge with the included key, so you won't need those pliers again for that. The whole process is shown with photos in our guide to installing a water filter. Combining it with a Quooker is no problem: the filter goes before the Quooker system on the cold water supply.

If you're looking specifically at this substance, we have a dedicated page with everything we know about it, from standards to choice: the water filter against PFAS. And if you just want to see what fits under your sink, take a look at the fixed filters in our range.

What does filtering PFAS cost per year?

The PureFilter Mineral+ costs €149.00 including the first filter. If you want stock straight away, the version with one extra refill filter costs €199.00, and the one with two extra refill filters costs €239.00. A separate replacement filter costs €65.00.

The lifespan depends on the size of your household. For 1 to 3 people, a filter lasts around twelve months, which works out at roughly less than one cent per litre. For 4 to 6 people, a filter lasts around six months, so roughly €0.27 per day. For comparison: with bottled water you can easily spend €1.00 to €2.00 per day, plus the hauling.

On top of that, your risk is limited: 40 days free returns and a 5-year guarantee. If you don't like it, it goes back. If you'd rather weigh up all the options calmly first, our overview of the healthiest water filter will help you further.

Frequently asked questions

Conclusion

Filtering PFAS isn't a matter of just buying a filter, but of choosing the right technique and replacing it on time. Activated carbon, ion exchange and reverse osmosis are the three routes that work. The figure to remember is 20 nanograms per litre: that's the limit NSF/ANSI 53 and 58 have set since 2022 for the combined PFAS concentration for the Total PFAS claim. Put that next to the Dutch statutory limit of 100 nanograms per litre and the RIVM guideline value of 4.4 nanograms per litre, and you know the order of magnitude you're talking about.

The honest answer to whether you should filter at home is: for PFAS alone, you usually don't have to, because Dutch tap water meets the limit and the biggest source is your food. If you want to tackle things more broadly, meaning PFAS as well as limescale, chlorine taste, lead, microplastics and pharmaceutical residues all at once, and you want that without refilling jugs, then a fixed filter on the pipe is the logical choice. At PureFilter we do that without reverse osmosis and with mineralisation as the final step: €149.00 one-off, then €65.00 a year for 1 to 3 people, with 40 days free returns and a 5-year guarantee.