Carlos Solis
A team from Guangzhou Medical University tested whether ordinary boiling followed by straining can remove nano- and microplastics (NMPs) from water. The researchers sampled both soft and hard water (the latter with higher mineral content), spiked the samples with manufactured nano- and microplastics, boiled them, skimmed off the sediment, and measured the remaining particles.
In hard water, heating causes calcium carbonate to precipitate—the same limescale you see inside kettles. As that scale forms, plastic particles can become trapped in the calcium crust and fall out of solution. You can remove those limescale particles carrying plastic by pouring the water through a regular tea strainer, the same kind used for loose-leaf tea.
How effective is it
- In some cases, boiling combined with filtration removed up to 90% of NMPs, though effectiveness depended on water type.
- Effectiveness rose from 34% at 80 mg/L calcium carbonate to 84% at 180 mg/L and 90% at 300 mg/L.
- In soft water with less dissolved calcium, the method removed about one-quarter of NMPs.
- Even when researchers added large numbers of nanoparticles, boiling and filtering still cut their counts significantly.
Why this matters
Earlier studies have found fragments of polystyrene, polyethylene, polypropylene, and polyethylene terephthalate (PET) in drinking water—materials we use every day in clothing, dishes, and household items. Since the start of mass plastic production, manufacturers have produced about 9 billion tons of plastic; much of that material has broken down over time into ever-smaller fragments, creating a global “plastic dust.”
Scientists do not fully understand how microplastics affect human health. Researchers have linked microplastics to disruptions in the gut microbiota and to increased antimicrobial resistance. A 2025 literature review from the University of Texas at Arlington suggests that a significant share of external exposure to microplastics may come from drinking water because wastewater treatment plants still fail to remove all the smallest particles.
Quick takeaways
- Boiling water and then straining the sediment can significantly reduce the amount of nano- and microplastics in drinking water, especially when the water is hard.
- The method does not remove every particle, but it offers an accessible, low-tech way to reduce how much microplastic you ingest from tap water.
Related coverage is available on ScienceAlert
Photo credit goes to Unsplash
