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Microplastics in drinking water: what the European Directive 2026/805 changes
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What if a large portion of the microplastics present in water is still escaping the European method used to measure them?

Since 2024, the European Union has had a harmonized methodology for measuring microplastics in water intended for human consumption. However, this method is limited to particles ranging in size from 20 µm to 5 mm.

Yet, a French study published in 2025 and conducted by researchers from the CRBE and Géosciences Environnement Toulouse yielded a particularly interesting result: 98% of the microplastics detected in the analyzed samples were smaller than 20 µm.

In other words, the majority fraction observed in this study fell below the lower threshold of the current European method.

Meanwhile, the new European Directive 2026/805, adopted on March 30, 2026, marks a new stage in the monitoring of microplastics in European waters. But be careful: contrary to what its connection to drinking water might suggest, it does not currently establish a new regulatory limit for microplastics in tap water.

For private individuals, local authorities, public establishments, and catering professionals, the challenge is therefore first to understand what is currently being measured, what is not yet being measured, and how this monitoring could evolve in the coming years.

European Directive 2026/805: what does it actually change?

Directive (EU) 2026/805 of the European Parliament and of the Council was adopted on March 30, 2026, and published in the Official Journal of the European Union on April 20, 2026.

It amends several fundamental texts of European water policy, particularly concerning surface water and groundwater.

Its objective goes well beyond just microplastics: it updates the monitoring of various emerging pollutants and contaminants present in the aquatic environment.

For the first time, the new rules explicitly provide for the inclusion of microplastics in watch lists concerning surface water and groundwater, as soon as sufficiently reliable and economically viable sampling and analysis methods become available.

The directive requires the European Commission to identify these methods no later than December 1, 2027.

The text also recognizes a direct link to drinking water: surface and groundwater constitute resources used to produce water intended for human consumption. The directive recalls that microplastics have been identified as a potential risk to human health, while specifying that more monitoring data is needed before the necessity of setting specific quality standards for surface and groundwater can be confirmed.

Member States must transpose the directive into their national law by December 21, 2027.

It would therefore be incorrect to claim that a new "drinking water microplastics standard" came into force in 2026. What is changing is the status given to microplastics in European water resource monitoring and the preparation of a more comprehensive analytical framework.

How are microplastics in drinking water currently measured?

To understand the issue, we must return to another European text: Commission Delegated Decision (EU) 2024/1441.

Adopted in March 2024, it establishes a harmonized methodology for measuring microplastics in water intended for human consumption.

The principle involves passing a large volume of water through a cascade of filters, then analyzing the collected particles using microscopy and vibrational microspectroscopy techniques such as µ-FTIR or µ-Raman.

The protocol requires sampling at least 1,000 liters of water. The particles are then characterized according to their size, shape, and the nature of the polymer.

However, the methodology has one essential limitation: it concerns particles between 20 µm and 5 mm. For fibers, the intended range also starts at 20 µm in length and extends to 15 mm.

The European particle classification thus starts with the category:

  • 20 to less than 50 µm;
  • 50 to less than 100 µm;
  • 100 to less than 300 µm;
  • 300 to less than 1,000 µm;
  • 1,000 to less than 5,000 µm.

Particles smaller than 20 µm are therefore not counted by this harmonized methodology.

Why does the 20 µm threshold raise questions?

This is where a French study published in 2025 provides particularly interesting insight.

Researchers from the Centre for Biodiversity and Environment Research (CRBE) and Géosciences Environnement Toulouse, units associated in particular with the CNRS, have developed a method to detect microplastics starting from 1 µm.

They analyzed ten brands of bottled water as well as a tap water sample taken in Toulouse.

The measured concentrations varied from 19 to 1,154 microplastics per liter depending on the samples. Seventeen types of polymers were identified.

But the most important result for understanding current regulations concerns size: 98% of the detected microplastics measured less than 20 µm.

They were therefore below the lower threshold of the European method defined in 2024.

This data must nevertheless be interpreted correctly.

It does not mean that "98% of the microplastics present in all French drinking water escape regulation." The study covered a limited number of samples: ten brands of bottled water and one tap water sample in Toulouse.

However, it shows something essential: when we improve the ability to observe smaller particles, a significant fraction that was previously uncounted can appear.

20 µm, 1 µm, 0.1 µm: what sizes are we talking about?

Micrometers are difficult to visualize.

A micrometer, or µm, corresponds to one thousandth of a millimeter.

A 20 µm particle therefore measures:

20 µm = 0.020 mm.

A 1 µm particle:

1 µm = 0.001 mm.

And 0.1 µm corresponds to:

0.1 µm = 0.0001 mm, or 100 nanometers.

This difference in scale is fundamental when talking about measurement as well as filtration.

A protocol capable of characterizing particles of several tens of micrometers does not automatically provide information on those measuring a few micrometers. And the reasoning becomes even more complex when we move down to nanometric particles.

Can compliant water contain uncounted microplastics?

Yes, and that is precisely why it is necessary to distinguish between regulatory compliance and the total absence of a substance or particle.

An analytical method defines what it is looking for, how it measures it, and the range in which it is capable of producing a harmonized result.

If the current European method for measuring microplastics starts at 20 µm, it does not allow one to conclude that smaller particles are absent. They simply lie outside the range covered by this methodology.

This is a principle found with many contaminants: the improvement of analytical techniques gradually allows for the search for substances or particle sizes that were previously much more difficult to characterize.

Directive 2026/805 is precisely in line with this logic of advancing knowledge. It provides for microplastics to join surface and groundwater watch lists when adapted methods become available.

Microplastics and nanoplastics: what is the difference?

The term "microplastic" itself covers an extremely wide size range. When a fragment becomes even smaller, one gradually enters the realm of nanoplastics, depending on the scientific or regulatory definitions used.

The smaller the size, the more technically complex their analysis becomes.

It is also for this reason that one must be cautious when two studies announce very different concentrations in drinking water. They have not necessarily looked for the same particle sizes or used the same analytical methods.

A study limited to particles larger than several tens of micrometers can logically find many fewer particles than a method capable of going down to 1 µm.

Comparing two figures without looking at their detection threshold can therefore lead to misleading conclusions.

Does your filtration system also handle particles smaller than 20 µm?

This evolution in knowledge also raises a very concrete question: what does the claim "filters microplastics" actually mean?

Two systems can claim to act on microplastics while having been designed or evaluated on very different size ranges.

To seriously compare technologies, several questions are therefore useful:

  • what is the stated filtration threshold?
  • does this threshold correspond to a nominal or absolute size?
  • what technologies are used?
  • what particle sizes were the performances evaluated on?
  • under what flow and pressure conditions?
  • are the performances documented by tests?

The simple word "microplastics" is therefore not enough to compare two pieces of equipment.

And one must avoid the reverse reasoning: just because a filter has a physical threshold smaller than the size of a particle does not mean that one can automatically attribute to it a precise percentage of removal for all families of microplastics and nanoplastics.

Why FLX Water works at a scale much smaller than 20 µm

At FLX Water, filtration relies in particular on hollow fibers calibrated at 0.1 µm, combined with electro-adsorption technology and high-density activated carbon, depending on the solution.

For purely dimensional comparison, 20 µm is 200 times larger than 0.1 µm.

This comparison helps to understand why particle size must be taken into account when choosing a filtration technology. However, it should not be interpreted as a demonstration of a 100% removal rate for all microplastics or nanoplastics.

Precise performance on a category of contaminants must be established under defined test conditions.

For individuals, the FLX Compact allows for water treatment centrally at the home's entry point. It combines high-precision 0.1 µm filtration, electro-adsorption, and activated carbon, without electricity or the addition of chemicals.

For professional and collective needs requiring higher flow rates, FLX Water also has treatment solutions scaled for these uses.

Local authorities and catering: why look below 20 µm now?

For a local authority, a public establishment, a restaurant, a cafeteria, or a hotel, Directive 2026/805 does not currently create an obligation to install a filter capable of retaining microplastics smaller than 20 µm.

It would therefore be incorrect to present an equipment change as a regulatory obligation stemming directly from the text.

On the other hand, the European evolution gives an interesting indication of the direction being taken by water monitoring.

The directive explicitly acknowledges that more data is needed regarding microplastics. It provides for their inclusion in surface and groundwater watch lists when sufficiently reliable methods are available and asks the Commission to identify these methods no later than December 1, 2027.

For managers, this can justify a proactive approach: knowing the real characteristics of installed equipment right now, the particle sizes they act on, and the tests that document their performance.

It is not a question of anticipating an obligation whose content is not yet fixed, but of avoiding discovering too late that the characterization of an equipment is based on an overly broad definition of the term "microplastics."

This approach can be particularly relevant when renewing an installation or designing a new water treatment project.

2026, 2027, 2030: what are the next European steps?

Several dates help to understand the regulatory trajectory.

2024: Decision (EU) 2024/1441 establishes a harmonized methodology for measuring microplastics in water intended for human consumption. It currently covers particles from 20 µm to 5 mm.

March 30, 2026: Adoption of Directive (EU) 2026/805.

April 20, 2026: Publication of the directive in the Official Journal of the European Union.

December 1, 2027: Deadline set for the Commission to identify reliable and economically viable sampling and analysis methods allowing for the integration of microplastics into surface and groundwater watch lists.

December 21, 2027: Deadline for transposition of Directive 2026/805 by Member States.

The directive also provides for deadlines in 2030 for certain measurement programs related to new water pollutants. But this does not mean that a new regulatory limit specific to microplastics in drinking water will automatically come into force in 2030.

As of today, it would therefore be premature to announce a "new microplastics threshold" for 2029 or 2030.

The trajectory is nonetheless clear: the European Union is seeking to produce more data, harmonize methods, and better characterize this pollution before any potential additional regulatory steps.

The real challenge: knowing what we are measuring… and what we are not yet measuring

The arrival of microplastics in European water monitoring policy is an important development. But perhaps one of the most interesting lessons does not come from a new limit value: it comes from the confrontation between available methods.

On one hand, the harmonized European method for drinking water currently starts at 20 µm.

On the other hand, a French study capable of going down to 1 µm found that 98% of the microplastics detected in its samples were smaller than 20 µm.

This result does not allow us to generalize this proportion to all European drinking water. But it shows why the definition of the measurement threshold is essential when talking about microplastics.

For consumers as well as professionals, the right question is therefore no longer just: "does my water contain microplastics?"

It also becomes: what particle sizes have we actually looked for?

And when it comes to treatment: what particle sizes is the technology used actually designed and documented to treat?

Frequently asked questions

Does European Directive 2026/805 impose a limit on microplastics in drinking water?
No. In particular, it strengthens the monitoring framework for surface and groundwater and provides for the integration of microplastics into watch lists when adapted sampling and analysis methods become available. It does not currently set a new maximum concentration of microplastics in tap water.

Why talk about a 20 µm threshold?
The harmonized methodology defined by European Decision 2024/1441 covers particles from 20 µm to 5 mm. Particles smaller than 20 µm are therefore not counted in this method.

Is it true that 98% of microplastics in drinking water are smaller than 20 µm?
A French study published in 2025 did indeed observe that 98% of the microplastics detected in its samples were smaller than 20 µm. However, it focused on ten brands of bottled water and one tap water sample in Toulouse. This figure should therefore not be generalized to all French or European drinking water.

Does a 0.1 µm filter automatically filter out all microplastics?
A threshold of 0.1 µm is well below the 20 µm threshold of the current European method. However, the nominal size of a filtration system is not enough on its own to establish a precise removal rate for all categories of microplastics and nanoplastics. Performance must be documented through appropriate testing.

Are local authorities and restaurants required to change their filtration before 2027?
Directive 2026/805 does not impose such an obligation. However, it may encourage operators to verify the characteristics and documented performance of their installations in order to anticipate the gradual improvement of monitoring methods.

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