Chinese researchers have found that simply boiling and filtering drinking water significantly reduces its nano- and microplastic content. The study showed removal rates ranging from 25% to 90%, depending on the water’s hardness.
A team led by biomedical engineer Zimin Yu at Guangzhou Medical University ran experiments in 2024 on both soft and mineral-rich hard tap water to measure how effective boiling is at removing microplastics from drinking water. The researchers deliberately added nano- and microplastic particles to water samples, boiled them, and then filtered out the resulting sediment.
The results showed that the harder the water, the more effectively plastic particles settled out during boiling. As calcium carbonate content rose from 80 milligrams per litre to 180 and then 300 milligrams per litre, the removal efficiency for nanoplastics climbed from 34% to 84% and then 90%. In soft water, by contrast, the removal rate stayed at around 25%.
According to the scientists, as water heats up, calcium carbonate in hard water separates out and forms limescale that coats the plastic particles, effectively trapping them. This is the same process behind the white residue commonly seen inside kettles.
Once encased in this limescale coating, the plastic fragments can be separated out using an ordinary stainless steel mesh strainer of the kind used for tea. The research team also tested the method with higher concentrations of nanoplastics and observed similar reductions.
Yu and colleagues said drinking boiled water could be a practical, long-term way to cut human exposure to nano- and microplastics worldwide. They noted, however, that the practice is currently only a local tradition in certain regions.
Why microplastics are a concern
Earlier research has detected traces of plastics including polystyrene, polyethylene, polypropylene and polyethylene terephthalate in drinking tap water. According to a 2025 literature review published by the University of Texas at Arlington, a significant share of human exposure to microplastics comes from drinking water, since wastewater treatment plants cannot fully remove these particles.
Roughly 9 billion tonnes of plastic have been produced globally since plastic manufacturing began, and much of it has never fully decomposed, instead breaking down into fine particles that have spread across the planet.
The extent to which plastic residues harm human health remains unclear, but some studies have linked them to changes in the gut microbiome and rising antibiotic resistance. Yu and the team said their findings lay the groundwork for future research involving larger sample sizes.
The study was published in the journal Environmental Science & Technology Letters.
Source: ScienceAlert
