Boiling tap water can remove nano/microplastics, Chinese study finds

Tiny shards of plastic are turning up deep inside our bodies in worrying amounts, and a major route in is what we eat and drink.

In 2024, a research group in China reported a straightforward way to cut nano- and microplastics in water. They tested the approach using both soft water and hard tap water (which contains more dissolved minerals).

Boiling tap water to remove nano/microplastics (NMPs)

To run the experiments, the scientists deliberately added nanoplastics and microplastics to water samples. They then brought the water to the boil and, afterwards, filtered out any solid material that had formed.

"Tap water nano/microplastics (NMPs) escaping from centralized water treatment systems are of increasing global concern, because they pose potential health risks to humans via water consumption," the researchers write in their published paper.

Watch the video below for a summary of the findings:

Depending on the water type, the combination of boiling and filtering removed large proportions of the NMPs - in some trials, as much as 90 percent.

A key advantage is practicality: most households already have what they need to try it.

"This simple boiling water strategy can 'decontaminate' NMPs from household tap water and has the potential for harmlessly alleviating human intake of NMPs through water consumption," write biomedical engineer Zimin Yu from Guangzhou Medical University and colleagues.

Water hardness, calcium carbonate, and limescale trapping plastics

Hard tap water performed better, with higher proportions of NMPs removed. That’s because hard water readily develops limescale (calcium carbonate) when heated.

The same chalky coating commonly found inside kitchen kettles can form on the surface of plastic particles. As temperature changes push calcium carbonate out of solution, it builds a crust that effectively locks the fragments in place.

"Our results showed that nanoplastic precipitation efficiency increased with increasing water hardness upon boiling," the team writes.

"For example, from 34 percent at 80 mg L−1 to 84 percent and 90 percent at 180 and 300 mg L−1 of calcium carbonate, respectively."

Soft water contains less dissolved calcium carbonate, yet the process still captured roughly a quarter of the NMPs.

The researchers say the lime-coated plastic particles can then be taken out with a basic filter - for instance, a stainless-steel mesh strainer like the sort used for tea.

Previous work has detected pieces of polystyrene, polyethylene, polypropylene, and polyethylene terephthalate in drinkable tap water, which people consume daily in varying amounts.

To push their method further, the team dosed samples with even more nanoplastic particles and still found that the number present could be reduced effectively.

"Drinking boiled water apparently is a viable long-term strategy for reducing global exposure to NMPs," write Yu and team.

"Drinking boiled water, however, is often regarded as a local tradition and prevails only in a few regions."

The researchers hope this could become more common as plastic pollution continues to spread.

Why microplastics exposure keeps rising

Minuscule plastic debris has become a growing problem. Microplastics can come from clothing, kitchen tools, personal care products, and countless other everyday items.

Because these materials are so durable, they persist in the environment - including within the human body.

Not only are many people already contaminated by microplastics, but exposure continues daily, with limited regulation aimed at these hard-to-control particles.

A 2025 literature review from The University of Texas at Arlington suggests a substantial share of microplastic exposure may come from drinking water, as wastewater treatment plants are still not removing microplastics effectively.

Around 9 billion metric tonnes of plastic have been produced worldwide since plastic manufacturing began. Much of that material has gradually worn down into ever-smaller pieces without fully decomposing, creating fine plastic dust that now permeates the planet.

The review notes that wastewater treatment plants do capture many of these small particles - but not enough to prevent ongoing release.

Although the precise damage these plastics may cause in our bodies is not yet fully understood, they are clearly not something we should be ingesting.

Plastics have already been associated with shifts in the gut microbiome and changes in the body’s antibiotic resistance.

The authors of this study want further work to explore how boiling water might reduce the intake of synthetic materials - and whether it could help counter some of the worrying effects of microplastics now being reported.

"Our results have ratified a highly feasible strategy to reduce human NMP exposure and established the foundation for further investigations with a much larger number of samples," Yu and colleagues conclude.

The research was published in Environmental Science & Technology Letters.

An earlier version of this article was published in March 2024.