PFAS in the Frisian waters and your tap water
Wetterskip Fryslân, the Frisian water authority, found PFAS in all the Frisian waters it tested. Yet the tap water in Friesland contains little PFAS almost everywhere. Here you can read how that works, what the figures are and what you can do yourself.
See the figures Shop ZeroWaterHow much PFAS is in the Frisian waters?
- PFAS is present in all Frisian waters tested, from large lakes to small drainage ditches. That is the result of around 1,000 measurements at some 200 locations in 2024 and 2025.
- The tap water in Friesland meets the legal standard. For 99% of Frisians it is below half of the RIVM advice.
- On the Frisian mainland and on Vlieland, Vitens makes no drinking water from surface water, only from groundwater.
- For a small group (around 4,300 people) the level in the tap water is above the RIVM advice. According to regional broadcaster Omrop Fryslân, the concerns are mainly on the Wadden Islands.
- The RIVM says: just keep drinking tap water.
Measurements by Wetterskip Fryslân in surface water
| Water | PFOS (nanograms per litre) | Standard for PFOS in surface water |
|---|---|---|
| Jelsumer Feart, near Leeuwarden air base | average 280 (64 to 650) | 0.65 |
| Lytse Feart | average 117 | 0.65 |
| Dokkumer Ie | average 6 | 0.65 |
| Drainage ditches west of the air base | up to 62 | 0.65 |
| Drainage ditches east of the air base | up to 53 | 0.65 |
| All larger Frisian waters tested | 1 to 10 times the standard | – |
Why is there so much less PFAS in your tap water?
The drinking water in Friesland comes from groundwater, often from tens of metres deep. On the mainland, Vitens does not use the water from lakes, canals and ditches to make drinking water. That is why the levels in the tap are much lower than in the surface water.
Please note: the standard for surface water (0.65 nanograms of PFOS per litre) is a different standard from the RIVM advice for drinking water (4.4 nanograms per litre). The surface water standard protects nature and people who eat fish. So you can't compare the numbers one to one.
Still, it is important to keep an eye on it. Research by the province of Fryslân shows that PFAS is also present in the groundwater, and that the standards are sometimes already exceeded in deeper layers.
* Weighted by harmfulness (PFOA equivalents), using the calculation method of the RIVM (Dutch National Institute for Public Health and the Environment). Source: analysis by Greenpeace Netherlands based on measurement data from the ten Dutch drinking water companies (measurements up to the end of June 2026), September 2026. 659,810 of the 664,145 inhabitants of Friesland fall into the lowest category (0 to 2.2 ng/l); 3,580 inhabitants are between 4.4 and 6.6 ng/l and 755 inhabitants above 6.6 ng/l. ** Source: Wetterskip Fryslân, research 2024–2025 (June 2026) and the questions and answers about the Jelsumer Feart (average of 30 measurements up to April 2025). The surface water standard is the annual average environmental quality standard for PFOS. Levels may vary by location and by measurement.
What is PFAS?
PFAS is a large group of man-made substances. They are found in many things you use every day.
- Non-stick pans
- Rain jackets and outdoor clothing
- Food packaging
- Cosmetics and firefighting foam
Why is it called a ‘forever chemical’?
- PFAS hardly break down in nature.
- They enter rivers and groundwater through factories and products.
- That water is also used to make drinking water.
- They stay in your body for a long time.
How does PFAS end up in the Frisian waters?
Wetterskip Fryslân names a few important sources.
Firefighting foam at the air base
Wetterskip Fryslân measures the highest levels around Leeuwarden air base. PFOS from firefighting foam has ended up in the Jelsumer Feart and has spread over more than 1,100 hectares.
Discharges into the sewer
Of the 50 companies tested, 48 discharge measurable amounts of PFAS into the sewer. Wastewater treatment does not remove PFAS well.
Crop protection products
In arable farming areas, the water authority measures more TFA. This is a small PFAS that forms when some crop protection products break down.
Why PFAS deserves attention
The RIVM says: together, people in the Netherlands take in more PFAS than is good for our health. This comes mainly from food, but also from drinking water.
It builds up
Your body clears PFAS only slowly. Small amounts add up over the years.
Effect on your immune system
According to the RIVM, even small amounts of PFAS can make your immune system work less well.
The advice is stricter than the law
The RIVM advises 4.4 nanograms per litre. The law is less strict. Below you can read the difference.
Law and advice: what's the difference?
There are two numbers for drinking water you may read about. They don't measure exactly the same thing, but this is how it works:
- The law (EU, since 12 January 2026): a maximum of 100 nanograms per litre for 20 PFAS combined. Dutch tap water meets this standard.
- The RIVM advice: 4.4 nanograms per litre. Here the RIVM gives more weight to how harmful each type of PFAS is.
The advice is stricter because there is new knowledge about the effects of PFAS. The government is waiting for advice from the WHO before changing the law.
Good to know
- Tap water in the Netherlands is safe to drink, say the RIVM and the drinking water companies.
- For surface water there is a separate, much lower standard for PFOS: 0.65 nanograms per litre. It protects nature and people who eat fish.
- Drinking water made from groundwater (as in Friesland) contains less PFAS than drinking water made from river water (mainly in the west).
- Boiling does not remove PFAS from your water.
ZeroWater filters PFAS
The tap water in Friesland scores well, so just keep drinking it. Want to take in even less PFAS through your water? Then a certified filter is a simple extra step.
less PFAS in your water
This percentage applies to PFOA and PFOS, the two best-known and most studied PFAS. The ZeroWater 5-stage filter has been tested for these to the NSF/ANSI 53 standard and certified by the independent institute IAPMO. View the certificate.
Tested, certified
Not a promise, but an independently tested result. Tested with far more PFOA and PFOS than is found in Dutch tap water.
More than just PFAS
The filter is also certified for lead, chromium-6, mercury and chlorine. That makes your water taste purer too.
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Add to cartView product →Questions about PFAS in the Frisian waters
Can I still drink the tap water in Friesland?
Yes. The tap water in Friesland meets the legal standard and is below the RIVM advice almost everywhere. The RIVM and the drinking water companies advise you to keep drinking tap water. Want to take in less PFAS? Then you can filter your water as an extra step.
Can I swim in the Frisian waters and eat fish from them?
For most Frisian waters there is no separate advice. For the Jelsumer Feart and the Lytse Feart near Leeuwarden air base, the regional health service GGD Fryslân does advise not to swim there, not to eat fish from them and not to use the water for your vegetable garden. See the Wetterskip Fryslân website for current advice.
Does ZeroWater filter all PFAS?
The honest answer: ZeroWater is certified for PFOA and PFOS, the two best-known PFAS. There are thousands of types of PFAS. We have no certificate for the other types, so we don't make any promises about them.
Does the TDS meter show how much PFAS is in my water?
No. The meter measures dissolved solids such as limescale and metals. PFAS are present in such tiny amounts that a TDS meter can't measure them. The meter does help you see when your filter is used up: when it shows 006, replace your filter.
Does boiling or bottled water help?
Boiling does not remove PFAS from water. According to the RIVM and the drinking water companies, bottled water is not the answer, and it creates a lot of plastic waste. A filter on your regular tap water is a simpler alternative.
Where does PFAS in the Frisian water come from?
In Friesland, PFAS comes from sources such as firefighting foam at Leeuwarden air base, companies that discharge PFAS into the sewer, and crop protection products that break down into TFA. PFAS also reach the water through rain and the air. Because PFAS hardly break down, they stay in the environment for a long time.
Know what you drink
Just tap water, but with less PFAS. For you and your family in Friesland.
Shop ZeroWater Replacement filters- Wetterskip Fryslân – PFAS present everywhere in Frisian waters (June 2026). wetterskip.frl (in Dutch)
- Wetterskip Fryslân – PFOS in the Jelsumer Feart, questions and answers (updated July 2026). wetterskip.frl (in Dutch)
- NOS – PFAS in wastewater on Vlieland; Vitens uses no surface water for drinking water on the Frisian mainland and Vlieland (February 2025). nos.nl (in Dutch)
- Greenpeace Netherlands – PFAS tap water postcode checker and methodology, based on measurement data from the ten Dutch drinking water companies (September 2026). Article · Methodology (PDF) (in Dutch)
- Omrop Fryslân – PFAS in Frisian drinking water is low in most places, concerns on the Wadden Islands (September 2026). omropfryslan.nl (in Dutch)
- RIVM (Dutch National Institute for Public Health and the Environment) – PFAS in drinking water. rivm.nl/pfas/drinkwater
- EU Drinking Water Directive 2020/2184 (PFAS standard in force since 12 January 2026). eur-lex.europa.eu
- ZeroWater Performance Data Sheet, IAPMO certification to NSF/ANSI 53 and 42. View PDF
ZeroWater is certified for the reduction of PFOA and PFOS. Results were achieved under laboratory conditions; actual results may vary.