Microplastics are found in tap water and bottled water.

What microplastics are and just how small they can get

Microplastics refer to synthetic plastic particles ranging in size from one micrometre to five millimetres. A micrometre is one thousandth of a millimetre. Most of them cannot be seen with the naked eye.

Nanoplastics are even smaller: less than one micrometre, smaller than a human cell. These particles can penetrate cell membranes and spread throughout the body. This is precisely what makes them particularly interesting and worrying from a scientific perspective.

The sources are varied. Microplastics are formed when larger plastic products break down in the environment: packaging, bottles, films. However, they are also manufactured specifically, for example as microbeads in exfoliants and toothpaste. The largest sources of microplastics are, however, less obvious: synthetic textiles release hundreds of fibres with every wash. Tyre wear on roads generates particles that are washed into waterways by rain. And cosmetic products contain plastics that end up in the sewer system via the drain.

How microplastics enter drinking water

The route is via wastewater. Wastewater treatment plants in Switzerland and Germany use multi-stage processes and, depending on the plant, remove between 95 and over 99% of microplastic particles. That sounds like a lot, but given the enormous volumes of water treated daily, particles still end up in rivers and from there into the groundwater.

In Geneva, a study investigated microplastic contamination in drinking water: 25 to 55 particles per cubic metre were measured in the raw water. After treatment with sand filtration and activated carbon, the figure was zero to four particles. The treatment therefore works, but does not reduce the level to zero.

A figure that surprises many: bottled water contains, on average, significantly more microplastics than tap water. A study by Ohio State University showed that bottled water contained around 10 particles per litre, whereas tap water contained around 4.5 particles. Other studies have found even greater differences. The reason: during the bottling, storage and transport of plastic bottles, particles are released from the bottle material. People who drink tap water instead of bottled water generally ingest fewer microplastics.

What microplastics do to the body

Microplastics have now been detected in human blood, the liver, the kidneys, the placenta and even in saliva. The particles enter the body via food and drinking water and are distributed via the bloodstream.

The health effects are currently the subject of intensive research. What is known so far is that microplastics can trigger inflammatory reactions in the gastrointestinal tract. Particularly problematic are the chemical additives contained in many plastics. Plasticisers such as phthalates and bisphenol A (BPA) are not firmly bound to the plastic and can be released into the body. They are suspected of disrupting the endocrine system and causing oxidative stress.

Furthermore, studies suggest possible links to metabolic disorders, impairments of the immune system and an increased risk of cardiovascular disease. There is currently insufficient data to make reliable statements about specific long-term effects in humans. The World Health Organisation (WHO) currently classifies the risk posed by microplastics in drinking water as low, but emphasises the need for further research.

One thing is clear: microplastics do not belong in the human body. And exposure can be reduced.

Why there are no limit values yet

Unlike heavy metals or PFAS, there are as yet no binding limit values for microplastics in drinking water. Neither in the EU nor in Switzerland. The reason: there is currently no standardised measurement method. How can one regulate something that cannot be measured uniformly?

In May 2024, the EU adopted a harmonised measurement methodology that detects particles between 20 and 5,000 micrometres. Eight EU countries began standardised sampling at pilot sites in 2025. A full risk assessment is expected by 2029, on the basis of which limit values can then be set.

In December 2025, Switzerland updated its Chemicals Risk Reduction Ordinance and introduced new restrictions on intentionally added microplastics in products. This applies, for example, to cosmetics and cleaning products. However, there are still no limit values for microplastics in drinking water here either.

A critical point: the EU measurement methodology only detects particles of 20 micrometres or larger. Research shows, however, that the majority of microplastic contamination in drinking water consists of smaller particles. The regulation is therefore a step forward, but not a complete one.

Which filters remove microplastics

Boiling is only partially effective. A study from 2024 showed that boiling mineral-rich water for five minutes can remove up to 90% of microplastic particles, as the particles bind to mineral deposits and settle out. However, this does not work with soft, low-mineral water, and the smallest nanoplastic particles are not captured. Filtration is the more reliable method.

Ceramic filters have pore sizes in the range of 0.2 micrometres. This enables them to mechanically retain the majority of microplastic particles. In combination with activated carbon, which binds dissolved pollutants through adsorption, a broad filtration spectrum is achieved. Effectiveness depends on the fineness of the ceramic and the quality of the activated carbon.

Activated carbon block filters on their own also offer a certain degree of protection, particularly against larger particles. However, they are less effective against the smallest microplastic fragments measuring less than five micrometres.

Reverse osmosis achieves the highest removal rates: over 99.9%, even for nanoplastics. The membrane pores are around 10,000 times smaller than the smallest microplastic particles. However, the system requires electricity, produces wastewater and also removes minerals. Furthermore, recent studies show that aged RO membranes can themselves release microplastic fragments if they are not replaced in good time. Regular maintenance is therefore crucial here too.

Our approach at MAUNAWAI

Our filter systems combine mineral ceramics and high-performance activated carbon in a multi-stage process. The ceramic layers mechanically trap particles, whilst the activated carbon binds dissolved pollutants. Thanks to slow gravity filtration, the water remains in contact with the filter media for a long time, which improves adsorption.

For microplastics, the Kini filter jug reduces contamination by around 70%, and with the additional micro-sponge by around 85%. This is significantly more than conventional ion-exchange jug filters achieve, which, due to their design, barely retain any microplastics. For heavy metals and PFAS, our systems even achieve removal rates of over 99%. We communicate all figures openly because transparency is more useful to you than a sugar-coated promise.

At the same time, it is worth bearing in mind that the largest source of microplastics when drinking does not come from the tap water itself, but from plastic bottles. Anyone switching from bottled water to filtered tap water significantly reduces their microplastic intake through this change alone.

Our Pi technology works with 21 natural mineral ceramics. Over 99% of pollutants such as heavy metals, PFAS and pharmaceutical residues are removed, whilst minerals are retained. No electricity, no chemicals, no wastewater. You can find the full test results under Science and Studies.

What you can do now

Cut down on plastic wherever possible. Drink tap water instead of bottled water. Use glass or stainless steel water bottles. When buying cosmetics and cleaning products, look for microplastic-free options.

And if you’d like to filter your tap water further: choose a system with proven filtration performance for specific contaminants. Not every filter removes everything equally well. Ask questions, compare options, and request test results.

We’d be happy to advise you. Contact us or discover an overview of all MAUNAWAI systems.