There's a Surprisingly Easy Way to Remove Microplastics in Your Drinking Water

Tiny shards of plastic are finding their way deep into our bodies in worrying amounts, largely through what we eat and drink.

In 2024, a research group in China reported a straightforward, effective way to remove these particles from water. Scientists from Guangzhou Medical University and Jinan University tested the approach using both soft water and hard tap water (which contains more dissolved minerals).

"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 from Guangzhou Medical University and Jinan University write in their published paper.

Boiling tap water to reduce nano/microplastics (NMPs)

To run the experiments, the team introduced nanoplastics and microplastics into water samples, boiled the liquid, and then filtered out any precipitates that formed.

In some scenarios, the boiling-and-filtering method removed up to 90 percent of NMPs, although the results depended on the type of water being treated. A key advantage is its practicality: most households can do this using standard kitchen equipment.

"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.

Why hard water performed better: limescale (calcium carbonate)

The researchers found that hard tap water tended to shed a larger share of NMPs during boiling. Hard water naturally forms limescale (calcium carbonate) as it heats, and that chalky deposit-familiar to anyone who has looked inside a kettle-can build up on the surface of plastic particles.

As temperature changes drive calcium carbonate out of solution, the mineral coats and traps the tiny plastic fragments within a crust, helping remove them from the water.

"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."

Even with soft water-where there is less dissolved calcium carbonate-around a quarter of NMPs were still captured and removed from the water.

According to the researchers, the lime-coated plastic pieces can then be taken out using a basic filter, such as a stainless-steel mesh strainer of the sort used for tea.

What has been detected in tap water, and why this matters

Earlier studies have reported fragments of polystyrene, polyethylene, polypropylene, and polyethylene terephthalate in drinkable tap water-materials many of us may be ingesting daily in differing amounts.

To push the method further, the team increased the number of nanoplastic particles added to the test water, and still found the particle count could be cut substantially.

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

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

The authors suggest that, as plastics continue to proliferate worldwide, boiling tap water could become more widely adopted.

Health implications and next research steps

It is not yet fully clear exactly how harmful these plastics are once inside the body, but they are hardly a beneficial addition to anyone’s diet.

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

The team behind the study is calling for further work on how boiling could help limit the intake of artificial materials through drinking water-and whether this could help counter some of the concerning effects linked to microplastics.

"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," write the authors.

The research has been published in Environmental Science & Technology Letters.

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