Washing machines are usually unable to filter out the microplastic fibres in our textiles that break off during washing. Thus, the fibres enter the sewage treatment plants with the household wastewater. However, countless particles escape the filter systems and end up in our environment. According to a study by the University of California in Santa Barbara, on average 60% - 99% of microplastic particles are filtered out of the water. In Germany, only 20 out of about 10,000 sewage treatment plants have the so-called purification stage 4, whose main aim is to rid our wastewater of medicine residues.Microplastic fibres are particularly difficult to filter out. Due to their shape and floating properties, they pass through the filter systems much more frequently than other types of microplastics such as pellets, so-called microbeads from cosmetics and other plastic fragments.  But even if they are filtered out, the plastic particles often end up back in the environment with the sewage sludge. If the sewage sludge is not incinerated, it is used as fertiliser on fields. From here, the microplastic particles bound in the sewage sludge make their way back into our oceans. So-called combined sewer overflows are another problem. They serve to relieve the sewage system in the case of heavy rain. In order to prevent backwater in households during heavy rainfall, the wastewater flows through the sewers untreated when the volume of water is high. By the way, the wastewater from the gullies does not pass through a sewage treatment plant, but flows mostly unfiltered into our waters. The microplastic particles from tyre and shoe sole abrasion, as well as microplastic fibres found in the air and in sewage sludge, therefore pollute our environment directly. For technical reasons, the filtering possibilities of sewage treatment plants are unfortunately not sufficient to prevent the pollution of the oceans by microplastics. However, by rethinking our buying habits and mindful washing behaviour, everyone can contribute to reducing the amount of microplastics entering the environment.