Filtering microplastics out of drinking water
How microplastics get into drinking water, how dangerous they are according to current knowledge and how an activated carbon block filter reliably filters them out.
Today, microplastics are found in soils, oceans, the air and water. Small amounts also come out of the tap. This guide explains what microplastics are, how they get into drinking water, how dangerous they are according to current research and how an activated carbon block filter reliably retains them.
What are microplastics?
Microplastics are plastic particles between 0.1 µm and 5 mm in size. For comparison: at around 100 µm, a sheet of paper is about a thousand times as thick as the smallest particles of 0.1 µm. At 5 mm, the largest particles reach the length of a red ant. Particles smaller than 1 µm are called nanoplastics. The term covers all plastics, i.e. polymers ranging from packaging material to textile fibres.
Experts distinguish between two types:
- Primary microplastics are deliberately manufactured as a material, for example for exfoliating scrubs, toothpaste, cosmetics, cleaning agents, varnishes and paints.
- Secondary microplastics are formed when larger plastic waste breaks down due to ultraviolet light (UV light) and movement. The largest single source is the abrasion of car tyres. Fibres are also released when clothes made of polyester, polyethylene or elastane are washed.
How do microplastics get into drinking water?
Microplastics reach drinking water mainly via three routes: textile fibres from laundry, the abrasion of car tyres and sewage sludge used in agriculture. The exact proportions are still being researched, but practically every household contributes. Fine fibres come loose when synthetic clothing is washed. Through tyre abrasion, large quantities enter the sewer system after rainfall. Conventional sewage treatment plants only partially retain microplastics. A large proportion ends up on the fields via sewage sludge and returns from there to the water cycle. This connection was documented in 2017 by a widely noted study by the investigative network Orb Media.
How much microplastic is in drinking water?
A 2014 study by the Alfred Wegener Institute (AWI) found between 86 and 714 microplastic particles per cubic metre of water. Depending on the size of the plant, between 93 million and 8.2 billion particles thus enter rivers. A worldwide analysis by the University of Minnesota with Orb Media tested around 150 drinking water samples: 80% contained microplastics. In Germany, the proportion is lower than in many other countries. Samples from Hamburg and Dortmund contained around two and a half particles per litre.
How dangerous are microplastics?
According to current research, microplastics in drinking water are considered to pose little health concern. In 2019, the World Health Organization (WHO) evaluated the available studies and rates the measured level as acceptable, while noting that data are limited. Researchers' real concern is less the particles themselves than their role as carriers.
Because of their water-repellent (hydrophobic) surface, microplastic particles bind environmental toxins such as dioxin. They also offer bacteria a surface on which a biofilm forms. The Alfred Wegener Institute has shown that pathogens use microplastics as a means of transport. Via animals that ingest such particles, microplastics enter the food chain and thus our food.
A second route is via the respiratory tract. Some of the particles are similar in composition to fine particulate matter. Researchers are therefore examining possible effects on the lungs, heart and circulation. A study by the Vrije Universiteit Amsterdam, published in the journal Environment International in 2022, proves that the particles reach the human body. The researchers found plastic particles in 17 of 22 blood samples, including PET (polyethylene terephthalate) and polyethylene. The long-term consequences remain unclear. Experts point to the precautionary principle and draw a comparison with asbestos, whose dangers were recognised only late.
You can already reduce the exposure in your own drinking water today. An activated carbon block filter reliably retains microplastics together with the pollutants adhering to them, while research works towards definitive answers.
Are there limit values for microplastics in drinking water?
Fixed limit values for microplastics in drinking water are still pending. The German Drinking Water Ordinance strictly regulates water quality and keeps an eye on microplastics. At EU level, the Drinking Water Directive of late 2020 put the topic on the agenda for the first time. Since then, microplastics have been on a watch list. It prepares the ground for uniform measurement methods and possible requirements. Until reliable values are available, filtering your own water remains the most direct way to reduce exposure.
How do you filter microplastics out of water?
Several filter media are suitable for removing microplastics, including activated carbon, ceramic, hollow-fibre membrane and ultrafiltration membrane (UF membrane). What matters is the pore size in relation to the particle size. As microplastics in tap water are usually larger than one micrometre, a fine-pored filter is sufficient for household use. The two most common approaches are reverse osmosis and activated carbon.
Reverse osmosis and ion exchange
Reverse osmosis filters work with a pore size of about 0.001 µm and retain even nanoplastics. This comes at a high price: they also remove valuable minerals and salts, which is why the water then has to be treated again. For household use, this effort is usually disproportionate.
Activated carbon block filter
Activated carbon comes in the form of loose granules and as a solid block. For household use, the activated carbon block filter is the most suitable. Its dense structure acts like a fine sieve for microplastics and, thanks to the adsorptive properties of the carbon, also binds dissolved pollutants. Valuable minerals remain in the water.
Mineral water instead of tap water?
Mineral water only seems to get around the problem. Water from PET bottles can contain more microplastics than tap water, because particles come loose from the inner walls of the bottles. Add to that lugging crates, bottle deposits and a poorer carbon footprint. Filtered tap water is the cheaper and often cleaner alternative.
Filtering microplastics with Alb Filter
Alb Filter drinking water filters rely on sintered activated carbon Made in Germany. The block retains microplastics together with adhering pollutants and leaves minerals, salts and trace elements in the water. This means clean drinking water comes straight from the tap. That saves lugging crates and packaging waste.
Related to this topic
Filtering microplastics with Alb Filter
Alb Filter drinking water filters rely on sintered activated carbon Made in Germany. The block retains microplastics together with adhering pollutants and leaves minerals, salts and trace elements in the water. This means clean drinking water comes straight from the tap. That saves lugging crates and packaging waste.
Frequently asked questions
Can microplastics be filtered?
Yes. As microplastics in drinking water are usually larger than one micrometre, a fine-pored activated carbon block filter reliably retains the particles.
Are microplastics harmful?
At the levels measured today, microplastics in drinking water are considered harmless to health according to the WHO, although the data are thin. Their role as carriers of environmental toxins and germs is considered particularly critical. As studies have now even detected the particles in human blood, researchers recommend taking precautions.
Does tap water contain microplastics?
Yes. In 2014, the Alfred Wegener Institute detected between 86 and 714 particles per cubic metre of water. The amounts vary depending on the region and source.
How much microplastic is in German drinking water?
The proportion is lower in Germany than in many other countries. In samples from Hamburg and Dortmund, investigators found around two and a half particles per litre. Representative nationwide measurements are still pending.
How do microplastics end up in drinking water?
Through the abrasion of car tyres, textile fibres from laundry and sewage sludge on fields, microplastics enter the water cycle and from there get into tap water.
Which filter removes microplastics best?
For household use, an activated carbon block filter is the best choice. It retains microplastics, binds pollutants and at the same time preserves the minerals in the water.
The following neutral specialist sources serve as the basis:
Sources
- Umweltbundesamt (German Environment Agency): Definition, occurrence and assessment of microplastics (https://www.umweltbundesamt.de/service/uba-fragen/was-ist-mikroplastik)
- World Health Organization (2019): Microplastics in drinking-water (https://www.who.int/publications/i/item/9789241516198)
- Leslie et al. (2022), Environment International: Discovery and quantification of plastic particle pollution in human blood (https://doi.org/10.1016/j.envint.2022.107199)
- Directive (EU) 2020/2184 on the quality of water intended for human consumption (https://eur-lex.europa.eu/eli/dir/2020/2184/oj)
