Photo Illustration by Amelia Manley for Verywell Health; Getty Images
While some fancy filtration methods can help remove tiny plastics from your tap water, a recent study proposes a simpler solution: boiling your water. Basin Faucet Bathroom
The study, published last month in Environmental Science & Technology Letters, showed that boiling tap water and then filtering it can remove nearly 80% of the nanoplastics and microplastics (NMPs) present.
“These tiny plastics are getting into our body via drinking water with uncertain health risks,” contributing study author Zhanjun Li, PhD, a professor in the School of Biomedical Engineering at Guangzhou Medical University, told Verywell in an email. “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.”
Here’s how it does—and doesn’t—work.
Li and his colleagues gathered hard and soft tap water samples from Guangzhou, China, and added varying concentrations of nanoplastics and microplastics. They then boiled the water samples for five minutes and allowed them to cool. Afterward, they remeasured the samples for free-floating plastic content.
Hard tap water refers to water that contains a higher concentration of minerals, such as calcium and magnesium, Anna Gitter, PhD, an environmental researcher with UTHealth Houston School of Public Health, told Verywell in an email. Soft tap water refers to water that does not have excess concentrations of these minerals.
Boiling hard tap water creates limescale, a chalky white deposit primarily composed of calcium carbonate (CaCO3). As the water increases in temperature, CaCO3 undergoes a chemical reaction and precipitates out of the water, forming incrustants, or little crystals. These solid particles wrap and clump around the tiny plastic particles, making them a lot larger, Li said. As a result, they become big enough to filter out.
In hard tap water samples that contained 300 milligrams of CaCO3 per liter of water, the researchers were able to use the boil-and-filter technique to remove up to 80% of free-floating NMPs, including polystyrene, polyethylene, and polypropylene.
Soft tap water samples were trickier. In soft tap water samples with less than 60 milligrams of CaCO3 per liter of water, researchers removed only about 25% of NMPs after boiling the water.
It’s important to note that boiling tap water itself does not remove the plastic or make it disappear, Sasha Adkins, PhD, MPH, senior lecturer in Environmental Health Sciences at the University of Massachusetts Amherst, told Verywell in an email.
“All it does is trap it [plastics] in clumps with the minerals in the water, which—and this is the critical step—could be left behind when you pour the water through a filter with small enough pores,” Adkins said. “But make sure you aren’t pouring hot water through a plastic water filter, or you are defeating the purpose.”
Spots on glassware, stains on surfaces, and mineral buildup in pipes or water heaters can be signs that you have hard water, Gitter said.
An increase in residue or white or greenish build-up around your faucet is another sign of hard water, Arie Francis, MD, an emergency medicine physician who specializes in medical toxicology and emergency medicine at Stony Brook Medicine, told Verywell.
If you’re not sure what type of water you have, you can buy test kits that measure the hardness of water, both Francis and Gitter said. You’ll need to collect a sample and mail it to a lab for testing. You can also review your water utility company’s annual water quality report, also known as the consumer confidence report, to learn more about your tap water.
According to Li, boiling your water for approximately two to five minutes effectively promotes the precipitation of minerals and the entrapment of microplastics. “The incrustant-forming process is very fast. We don’t think too long of time boiling will make a significant difference,” he said.
Last month, a study made headlines for revealing that a typical liter of bottled water contains nearly a quarter million plastic particles—10 to 100 times more than previously estimated. Experts offered a rather bleak read of the situation: There’s not much you can do to avoid it.
So why are things looking better for tap water—specifically hard tap water?
“I assume that given tap water is not stored in a plastic bottle, that there would be a lower concentration of micro and nanoplastics in tap water than bottled water,” Gitter said.
A 2019 study found individuals who meet their recommended water intake through only bottled sources may be ingesting an additional 90,000 microplastics a year, compared to 4,000 microplastics for those who consume only tap water, Adkins added.
Tap water and bottled water also differ in their sources, regulations, and cost. For instance, tap water comes from municipal water supplies and undergoes treatment to meet safety standards, whereas bottled water comes from various sources, including springs and wells, and may not have to undergo additional treatment.
More research is needed to determine how plastic particles in tap water impact human health.
“The concern with nanoplastics is that they are small enough to potentially interact with our body on a cellular level, and what these human health effects are remains unknown,” Gitter said.
Despite the uncertainties, there are plenty of hypotheses about what NMPs can do to your health.
Previous research indicates that exposure to these micro and nanoplastics may be associated with health effects like liver and gastrointestinal toxicity.
Adkins said that other research suggests microplastics appear to affect the ability of red blood cells to carry oxygen, cause the death of human embryonic kidney cells, and alter the permeability of the intestine.
“That means that our gut can’t do its gatekeeping job of deciding what is absorbed in our bloodstream—letting in what is nutritious and keeping out what is potentially harmful,” Adkins said.
Other studies have shown that exposure to nanoplastics can lead to other toxicological effects, including reproductive abnormalities, oxidative stress, gastrointestinal dysfunction, and increased mortality.
“All that evidence is just based on the physical properties of the plastic, and doesn’t even consider the additives or adsorbed contaminants that may be released from it,” Adkins said.
Aside from boiling and filtering your tap water, there are some things you can do to reduce your exposure to nanoplastics and microplastics.
Boiling your tap water for two to five minutes, followed by filtering it, may help remove nanoplastics and microplastics. But experts say further research and testing is needed to prove this.
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By Alyssa Hui Hui is a health news writer and former TV news reporter. She was the 2020 recipient of the Midwest Broadcast Journalists Association Jack Shelley Award.
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