Is it true that microplastics are present in drinking water?
This claim is certainly true. Microplastics have indeed been identified in drinking water. However, knowledge of the scope and impacts on human health is scarce. According to the limited number of studies available, groundwater is relatively well protected and contains few plastic particles. Water sourced from porous stone or rivers or dams contains more microplastics which would need to be removed through costly water purification technology. It is not known yet which techniques can clear all microplastics. To fully understand the occurrence and impacts of micro- and nanoplastics in drinking water for human health, more research and methodological harmonization are needed.
Detailed information
A 2019 report by the World Health Organization saw little reason for concern given current knowledge of plastics in drinking water. However, the same report also noted the lack of reliable studies and comparable data to allow us to fully understand the issue.
A 2023 review counted less than 20 publications on groundwater plastic pollution. It noted that many important aquifers around the world have not yet been studied and some regions are specifically understudied. Available studies of microplastic concentrations in groundwater varied between 0 and 97 particles per liter - this variation is likely to be due to the different methodologies used.
Generally, groundwater is filtered through stone and sand, and this natural filter cleans it from contaminants. However, if the stone is more porous, contaminants can make their way down more easily. Water from such aquifers must be monitored and purified before it can be used as drinking water.
Sometimes underground aquifers are recharged artificially with water. This is called Managed Aquifer Recharge (MAR). The primary purpose of this procedure is to augment the drinking water and irrigation supply, enhance water quality by diluting the pollutants present in the aquifer, and act as a drought protection measure. However, at times, wastewater is also employed. Since micro- and nanoplastics aren’t completely removed in wastewater treatment plants, using this method may lead to groundwater contamination.
Some drinking water is drawn from the surface, such as rivers or dams. Since this water doesn’t pass through a natural stone or sand filter, it must also be monitored and purified.
However, a lack of methodological harmonization and reliable knowledge on the effects of microplastics are big obstacles.* Plastics can also enter drinking water on their way to the consumer. For example, tap water passes through plastic pipes and valves on its way to households. These plastic parts can degrade over time, shedding particles into the water. Another way plastics can enter drinking water is through glass and plastic bottles. Reusable bottles, for example, are cleaned upon return. In this process, small fragments from plastic labels or caps can remain within the cleaned bottle.
Another question concerns the presence of nanoplastics in drinking water. Microplastics can break down into tiny sizes, which can be up to a 1000 times smaller than the smallest microplastics. Detecting nanoplastics in samples is a major analytical challenge. It is still unclear if and to what extent nanoplastics are abundant in nature and what the potential consequences are.
Humans can ingest plastics through air and food, so water is just one pathway for consumption. Research into the risks of micro- and nanoplastics for our bodies is still emerging. Even though the impacts aren’t clear yet, it makes sense to minimize the presence of plastics in the environment, in the air, water and food as much as possible, to avoid potential future harm.
*While Californian water regulators approved the world's first requirements for testing microplastics in drinking water sources, such regulation and official standards are still lacking in Europe (despite respective ongoing activities in the frame of the Drinking water Directive (EU)).
From a global perspective, the degree of chemical-analytical harmonization is very limited in microplastic research. However, final and widely accepted standard methods such as from ISO (so far only drafts) and certified reference materials of well-characterized, environmentally relevant (concentrations, size, shape, surface chemistry etc.) and matrix-matched microplastics would form the basis for any monitoring and judgment of the effectiveness of filtration technologies aiming at microplastic removal.
Expert Check
Thanks toSedat Gündoğdu of Çukurova University andMaaike Vercauteren of Ghent University for scientific fact-checking,
Updated on: November 2, 2023