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Water quality 17 min reading time May 17, 2026 by Thomas van der Veen

Microplastics in tap water and bottled water: what research actually shows

Microplastics are present in virtually all drinking water, including in the Netherlands. But the difference between tap water and bottled water is large: a litre of bottled water contains on average ten to one hundred times more plastic particles than a litre of tap water, mainly due to the plastic packaging and the bottling process itself. A landmark American study from 2024 counted, for the first time, the even smaller nanoplastics and arrived at an average of 240,000 particles per litre of bottled water, about 90% of which were nanoplastics. For tap water, those nanoplastic figures have not yet been reliably measured, so exact ratios remain uncertain. What is clear: microplastics have been detected in human blood, brain tissue and in human placentas. The first epidemiological signals point to a link with cardiovascular disease, though a causal relationship has not yet been proven. For anyone wanting to lower their exposure, filtered tap water is almost always the better route than bottled water.

Microplastics in tap water and bottled water: what research actually shows

What microplastics and nanoplastics actually are

Microplastics are plastic particles smaller than 5 millimetres. The scientific lower limit of a microplastic is 1 micrometre (µm, or one-thousandth of a millimetre); anything below that is called a nanoplastic. For comparison: a human hair is about 50 micrometres thick. Microplastics are therefore still partly visible under an ordinary microscope; nanoplastics are not.

They originate in several ways. Primary microplastics are deliberately produced at that size. Think of plastic pellets that factories use as raw material, microfibres deliberately woven into synthetic clothing, or microbeads in cosmetics such as scrubs and toothpaste (banned in rinse-off cosmetics in the European Union (EU) since 2018, but still present in older products and certain imports). Secondary microplastics arise from the breakdown of larger plastic, and that is a more complex process than just “it falls apart”. According to a comprehensive review in Environmental Science: Advances (2025) and complementary research in Microplastics and Nanoplastics (2025), several breakdown mechanisms work together:

These processes usually work together. A PET bottle lying in the sun for weeks simultaneously undergoes UV degradation, thermal degradation and oxidation, accelerating the release of small plastic particles. According to an overview by the Dutch National Institute for Public Health and the Environment (RIVM), the three largest sources in the Netherlands are tyre wear on the road, plastic raw materials (pellets that leak from factories), and general plastic waste. Smaller sources include paint, clothing, artificial grass pitches and certain pesticides.

Bioplastics such as PEF from Avantium

A noteworthy exception comes from the Amsterdam-based company Avantium. They produce polyethylene furanoate (PEF), a plant-based alternative to PET made from plant sugars via their YXY technology. PEF is not a solution against microplastics on its own. As it breaks down, smaller particles are still produced, and Avantium itself emphasises that PEF is not biodegradable in the natural environment. What PEF does do is break down enzymatically faster (about 1.7 times faster than PET according to research), be industrially compostable, and unlike PET not accumulate in the environment for decades. Whether the microplastics released during that faster breakdown have comparable health risks has not yet been sufficiently studied. PEF is expected to appear on a larger scale in bottles and packaging in the coming years (including via Carlsberg’s Fibre Bottle), which does not solve the microplastics issue but may limit it.

Via the kitchen sink, the shower drain and the washing machine, many microplastics end up in the sewer and eventually in surface water. So the question is relevant: how much of that remains in the water coming out of our taps?

What is in Dutch tap water

The most detailed Dutch research to date was carried out by drinking water companies Dunea and Waternet together with Het Waterlaboratorium (HWL, The Water Laboratory), the research institute KWR Water Research Institute, and the RIVM. Researchers sieved 10,000-litre volumes of drinking water for 24 hours, both through the drinking water treatment plant and at six points in the distribution network. Their conclusion: after the complete treatment, an average of 18 microplastic particles larger than 0.05 millimetres remained per cubic metre (1,000 litres). A large share of the microplastics in the raw surface water is therefore removed by the drinking water treatment before it reaches the tap.

You need to be careful with these figures, and this is an important point. The Dunea/Waternet study only measures microplastics larger than 0.05 millimetres (50 micrometres). The analytical method for measuring smaller microplastics (1–50 µm) and nanoplastics (below 1 µm) was not yet sufficiently developed at the time. More recent research elsewhere in Europe with better equipment finds considerably higher counts, precisely because the smaller fraction is included. A study from Toulouse in January 2025, published in PLOS Water, found 413 microplastic particles per litre in a Toulouse tap water sample using automated Raman microspectroscopy — almost all smaller than 20 µm. For groundwater-sourced drinking water in Denmark, the concentration was about ten times lower. Dutch tap water is sourced about 60% from groundwater and is therefore likely closer to the Danish situation, but specifically comparable research using the latest methods is still missing.

This gives the tap water story a more honest frame: we don’t yet know the exact particle counts for Dutch tap water, including nanoplastics. What we do know is that drinking water treatment removes a large share of the incoming plastic, and that figures using comparable measurement methods are consistently much lower than for bottled water (see below).

The framework of three layers of normation applies here well. Legally, Dutch tap water meets all requirements of the Dutch Drinkwaterwet (Drinking Water Act) and the European Drinking Water Directive 2020/2184. Microplastics have been explicitly on the “watch list” of that directive since 2021: member states must set up monitoring in preparation for any future norms. Socially, there is growing attention: the European Commission’s Joint Research Centre published a measurement method for microplastics in drinking water in 2024, and as a perspective in Science (2025) noted, no country has yet established a legal norm for microplastics in drinking water. Individually, there is room for optimisation: anyone wanting to lower their exposure further has several options.

What is in bottled water

The picture for bottled water is fundamentally different. In January 2024, researchers from Columbia University and Rutgers University — two leading American universities with strong research programmes in environmental and chemical sciences respectively — published in Proceedings of the National Academy of Sciences (PNAS) what is to date the most detailed analysis. Using a new technique called stimulated Raman scattering microscopy (SRS microscopy), they were able for the first time to not only count nanoplastics but also chemically identify them, down to a size range of 100 nanometres.

What they found was striking: between 110,000 and 370,000 plastic particles per litre, with an average around 240,000. About 90% of those were nanoplastics. That is ten to one hundred times higher than earlier estimates, which depended on techniques that could only detect larger fragments.

The polymers found were recognisable: PET (the material of most disposable bottles themselves); polyamide (PA, a type of nylon used in water filters in the bottling process); polystyrene (PS); and polyethylene (PE). Professor of analytical chemistry Marja Lamoree (Vrije Universiteit Amsterdam) noted in a response to Dutch broadcaster NOS that this confirms the suspicion that both the bottles themselves and the filtration process during bottling are sources of nanoplastics.

Importantly: the researchers tested three internationally available brands without disclosing their names, and found no brand to be plastic-free. An earlier, broader study by Sherri Mason at the State University of New York from 2018 confirmed this on a larger scale: in 93% of 259 bottles examined from 11 brands in 9 countries, microplastics were found. On average 325 particles per litre (including particles between 6.5 and 100 µm), against 5.5 particles per litre in tap water using the same measurement method. That is roughly a 60-fold difference in direct comparison.

What about brands available in the Netherlands?

There is no comparably detailed study for specifically Dutch market brands. There are, however, some relevant data points. Bar-le-Duc states on its own website that it regularly tests its products and detects no microplastics. That is a claim conducted in-house, methodologically not comparable with university research using SRS microscopy or advanced Raman techniques. Spa acknowledges on its website that microplastics are found in both tap and bottled water, and points out that according to a French study by the Agence nationale de sécurité sanitaire de l’alimentation, de l’environnement et du travail (ANSES, the French food, environmental and occupational health & safety agency), soft drinks, beer and lemonade often contain more microplastics than bottled water itself. Glass bottles can sometimes even contain more microplastics than PET bottles due to caps and handling, not because of the glass but because of the filling process.

There is also an irony in the story. Bar-le-Duc is extracted at industrial estate Lage Weide in Utrecht from a depth of 140 metres, and Sourcy at the foot of the Utrechtse Heuvelrug (Utrecht Hill Ridge) from a comparable depth. Drinking water company Vitens uses the same Utrecht sources for the tap water in the region. Anyone living in Utrecht is essentially drinking the same water from the tap as what is sold nearby in plastic bottles, but without the plastic packaging.

What about elsewhere in the world?

The situation varies strongly by country and region. A systematic review from 2024 examined tap water in 34 countries and found microplastics in 87% of 1,148 samples, with concentrations spanning seven orders of magnitude. Notable findings:

The bigger picture: bottling, transport in plastic, and storage in warm conditions consistently add plastic to the water, regardless of the original source quality. What comes out is therefore not a reflection of what went in at the source.

Size class makes the difference

The difference between microplastic and nanoplastic is not just quantitative but functional. Particles smaller than 1 micrometre behave biologically very differently from larger fragments. They can pass through the intestinal wall, through lung tissue, through cell walls and, as recent research shows, through the blood-brain barrier and the placenta.

A few landmark studies carry the most weight here. In 2021, Antonio Ragusa and colleagues were the first to find microplastics in human placentas, collected after delivery from healthy pregnant women. This finding became known as “plasticenta”. In 2022, Heather Leslie at Vrije Universiteit Amsterdam demonstrated that microplastics are present in human blood from 17 of 22 donors examined. In 2024, the team of Matthew Campen at the University of New Mexico found microplastics in all 62 placentas examined, also collected after delivery following strict contamination-prevention protocols. A follow-up study in Nature Medicine (2025) furthermore showed that microplastics accumulate in human brain tissue, with significantly higher concentrations in samples from 2024 compared with 2016. That points to an increasing burden over a short period. Tonsil research in children found microplastics not only at the surface but also deep within the tissue, as researchers at Stanford described in an accessible overview.

Wei Min, the Columbia chemist who co-developed the SRS technique, put it sharply in interviews: the smaller the particle becomes, the easier it can be mistaken by cells for a natural component.

What we know about health effects

Here it’s important to be honest about what the research does and does not show. Most health studies at this point are observational or based on animal and cell models. Causality in humans is difficult to establish for a substance we can no longer avoid.

The most cited human research to date was published by Raffaele Marfella and colleagues in The New England Journal of Medicine (NEJM) in March 2024. They analysed plaque from the carotid artery of 257 patients undergoing endarterectomy (a procedure to remove narrowed plaque from an artery). In 150 of them, microplastics and nanoplastics were found in the plaque; in 107, none. After an average follow-up of 34 months, patients with plastics in their plaque had a 4.5 times higher risk of a composite endpoint of heart attack, stroke or death (hazard ratio 4.53; 95% confidence interval 2.00–10.27).

An important caveat: this is an observational study. It shows an association, not a causal relationship. Patients with more plastic in their plaque may have other exposures (air pollution, occupational exposure) that could explain the effect.

Other relevant signals from animal and cell research: endothelial dysfunction of blood vessel cells from polystyrene nanoplastics, disruption of the gut microbiome, inflammatory responses, and in pregnancy models accumulation of plastic particles in fetal organs. Hormone-disrupting effects of additives in plastics, such as phthalates and bisphenols (including BPA, bisphenol A), are better substantiated than the effects of the plastic particles themselves.

The RIVM consistently emphasises that Dutch tap water is safe, that there is not yet enough evidence of concrete health damage from microplastics, and that at the same time there is sufficient reason for further research. Both statements can be true simultaneously.

Tap water is not your largest exposure source

Something often overlooked in the discussion: water is far from the only route by which we take in microplastics. Research consistently shows that exposure via food, air and household plastics is at least as relevant. A research overview in Comprehensive Reviews in Food Science (2024) and npj Science of Food (2025) gives a good picture of the main sources. The numbers are often more striking than the water data:

This does not detract from the figures on tap water and bottled water. It places them in context. Anyone seriously concerned about microplastics would likely gain more from these kitchen and household adjustments than from addressing only the water source. At the same time: the water difference is dramatically large and relatively easy to address. For anyone wanting to switch to filtered tap water, our water filter guide compares the options per situation.

Can you filter microplastics out of drinking water

For anyone wanting to lower their own exposure further, filtering tap water is the most effective route. Not every filter technique works equally well.

Reverse osmosis (RO) is the most thorough technique for consumer use. A thin-film composite membrane has an effective pore size of approximately 0.0001 micrometres, smaller than virtually all nanoplastics. Independent lab tests and NSF/ANSI 58 certification (the international standard for RO drinking water systems) consistently show removal of more than 99% of micro- and nanoplastics. A well-maintained RO system produces water that is essentially plastic-free. The cost is higher installation, regular maintenance, and some water loss during production.

Nanofiltration, a less well-known but emerging technique, sits between ultrafiltration and reverse osmosis in pore size (around 1 nanometre). The Dutch company NX Filtration develops hollow fibre nanofiltration membranes that remove microplastics, nanoplastics, per- and polyfluoroalkyl substances (PFAS), pharmaceutical residues and pesticides from water in a single step, without prior chemical pre-treatment. The company demonstrated the technology at the Twentekanaal, a local canal previously considered too polluted for drinking water production, and produced drinking water quality there in a single step. In 2024, Queen Máxima opened the new factory in Hengelo. NX Filtration currently focuses on industrial and municipal scale, not on consumer systems, but it shows that nanofiltration as an emerging technique offers the possibility of addressing micro- and nanoplastics together with other micropollutants in one step. An interesting Dutch development for the water treatment sector.

Granular activated carbon (GAC) works on a different principle: it absorbs contaminants via a large internal surface area. Effective for chlorine, taste, odour and larger microplastics, but the pore sizes lie roughly in the range of 0.5 to 20 micrometres. Many microplastic fragments are caught, but nanoplastics largely pass through.

Ultrafiltration (UF) sits between GAC and reverse osmosis: pore sizes around 0.01–0.1 micrometres. Effective for most microplastics but insufficient for nanoplastics.

Pitcher filters such as BWT Vida work on the basis of activated carbon with an ion exchanger that replaces calcium with magnesium. Good for limescale, chlorine, lead, copper and taste, and with the magnesium addition a popular option for those who simply want better-tasting tap water. For microplastics and especially nanoplastics, this type of filter is not designed and provides limited to no reduction.

There is one important nuance. Older or poorly maintained RO membranes can themselves start releasing microplastics as the polyamide layer degrades, according to research. Timely replacement according to the maintenance schedule (usually 2 to 3 years for the membrane) is therefore important. The same applies to other filters: not replacing them not only reduces effectiveness, but can actively make the problem worse.

What this practically means

The difference between tap water and bottled water is large in virtually all scientific comparisons, even if the exact ratio is still subject to discussion. For microplastics, tap water is objectively the better choice.

Three scenarios give direction:

You mostly drink tap water. Your water-related exposure is low. Whether an extra filtering step is worthwhile depends on your other priorities. If you are already considering a filter for other reasons (PFAS, taste, limescale), it is a logical step. Otherwise, the gain here is probably marginal compared to kitchen adjustments (replacing plastic tea bags, no plastic cutting boards, not heating in plastic, glass baby bottles).

You mostly drink bottled water. This is where the biggest gain lies. Switching to plain or filtered tap water lowers your microplastic intake by multiple orders of magnitude. A reverse osmosis system, or even a good carbon filter, delivers water that contains considerably fewer plastic particles than any brand of bottled water. Bonus benefit: significantly less plastic waste and lower long-term costs.

You are pregnant or have young children. Given the findings on microplastics in placenta, brain tissue and children’s tonsils, a more precautionary approach is defensible. This applies mainly to avoiding plastic in food contact (no warm food in plastic, no plastic tea bags, glass or stainless steel baby bottles) and not so much to tap water itself, which already scores low. For anyone wanting to minimise exposure via drinking water further, an RO system on the tap is the most thorough option.

In all three cases: Dutch tap water meets all legal standards and is safe to drink from. What is described here is about personal optimisation and context, not about correcting a fault in the system.

For anyone wanting to switch to filtered tap water, we have honestly compared the available options per situation in our guide on the best water filter for the Dutch situation in 2026. It places reverse osmosis, carbon filters, pitcher filters and all-in-one solutions side by side with their actual performance, price and maintenance burden.

Sources

Primary studies — microplastics in water

Dutch sources

Breakdown and sources of microplastics

Health effects and biomonitoring

Other exposure sources

Policy, regulation and global context

Industry sources

Additional background

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