Good News: Water Treatment Plants Remove up to 99.9% of Microplastic from Drinking Water

microplastic contamination in water
The researchers found that biologically active slow sand filters retained over 99.9% of plastic particles, even those smaller than a thousandth of a millimeter across, the so-called nanoplastics. Source: Eawag

There is good news on the burning water contamination issue of the 21st century. For 4 years, the researchers from Swiss Federal Institute of Aquatic Science and Technology have been investigating microplastic whether local water treatment plants were up to the challenge of microplastic contamination. A filtration method that is already in use retains almost all plastic particles from tap water.

The Danger of Microplastic

By now it is common knowledge that plastic is not the most harmless and ecologically safest material. In 2021 there was an estimated 6.3 bln tons of non-degradable plastic waste around the planet. The trash only decomposes into small particles up to 5 mm in diameter. This type of contaminant — so-called microplastic — is probably the most pervasive and widespread of the kind and can be found virtually everywhere, including living beings.

Earlier this year, scientists have found microplastic for the first time in human blood and lungs. This once again proves its ability to infiltrate any matter or environment. We humans consume microplastic via the food we eat, the bottled water we drink, and even the air we breathe. Neither long-term or short-term impact of microplastic exposure on human health are known yet. However, there are suggestions that the particles may harm delicate organ tissues, emit toxins into blood, and cause vascular occlusion.

Sand Filters for Water Safety

Back in 2019, a group of Eawag researchers launched a project together with Zurich Water Works to assess microplastic contamination and the risks for the local population. In the 2022 research paper, they share the good news. The researchers found that biologically active slow sand filters retained over 99.9% of plastic particles, even those smaller than a thousandth of a millimeter across, the so-called nanoplastics.

“Third-party analyses failed to detect microplastics at the depths at which the lake water was collected (around 30 meters), so we assume that almost no nanoplastics will exist there either,” — Dr. Ralf Kägi, Department of Process Engineering at Eawag.

The method was first tested in a series of small-scale lab experiments. Then the team moved to the lake water treatment facility at the Zurich Water Works from which drinking water is funneled into homes, hospitals, and restaurants. In both instances, researchers could barely find any trace of polymers.

This means that some of our water treatment plants, which are already in place to decontaminate other types of pollution, also work against microplastic and nanoplastic particles. So, at least as far as nanoplastics are concerned, the tap water is safe for now.