Microplastics have infiltrated almost every corner of our environment, from the deepest oceans to the water coming out of our kitchen taps. While advanced filtration systems exist, they can be expensive and hard to maintain. Now, researchers have discovered a surprisingly simple and accessible way to remove microplastics from drinking water: boiling it. A study published in Environmental Science & Technology Letters found that boiling hard tap water can eliminate nearly 90 percent of the nano- and microplastics present by trapping them in limescale.
Boiling traps plastics in limescale
The process works through simple chemistry rather than complex technology. When you boil water, the heat causes chemical changes in the minerals dissolved within it. Specifically, in hard water – which is rich in minerals like calcium and magnesium – the heat forces calcium carbonate to precipitate out of the liquid.
This precipitation creates a chalky, white substance commonly known as limescale or incrustant. As this limescale forms, it does not just stick to the kettle; it acts like a trap. The crystalline structures of the calcium carbonate encapsulate the tiny plastic particles floating in the water.
Once the water cools, these plastic-filled mineral solids settle or float as a crust. According to the research team led by Zhanjun Li and Eddy Zeng, these solids can then be easily separated from the liquid. Because the plastics are locked inside the mineral crystals, a simple filtration step, such as pouring the water through a standard coffee filter, is enough to catch the floating debris and leave the water significantly cleaner.
Hard water works best
The effectiveness of this method depends heavily on the quality of your tap water. The researchers tested water samples with varying degrees of hardness to see how well the plastic-trapping mechanism worked.
They found a direct link between mineral content and plastic removal. In hard water samples containing 300 milligrams of calcium carbonate per liter, boiling removed up to 90 percent of the nano- and microplastics. The high mineral content provided plenty of material to form the “cages” needed to trap the plastic particles.
Soft water is less effective
In contrast, soft water contains fewer minerals, which means less limescale forms during boiling. In samples with less than 60 milligrams of calcium carbonate per liter, the boiling method removed only about 25 percent of the plastics. While this is still a reduction, it shows that the strategy relies on the presence of calcium to work efficiently. For households with soft water, boiling alone may not provide the same level of protection against plastic ingestion.
Simple steps to filter your water at home
You do not need laboratory equipment to replicate these results. The study suggests that this “decontamination” strategy can be easily adopted in a typical kitchen.
- Boil: Bring your tap water to a rolling boil for about five minutes. This ensures the chemical reaction that precipitates the calcium carbonate has time to occur.
- Cool: Let the water sit and cool down. During this time, the incrustants (the mineral solids trapping the plastic) will form and settle.
- Filter: Pour the cooled water through a filter to catch the solids. A paper coffee filter or a stainless steel mesh tea strainer is sufficient to remove the lime-encrusted plastics.
This process mirrors the traditional Asian practice of drinking boiled water, which was originally adopted to kill pathogens but now appears to offer a modern benefit against industrial pollution.
The health risks of microplastics
Reducing our intake of these particles is becoming a priority for health researchers. Nano- and microplastics (NMPs) are fragments ranging from 5 millimeters down to 1 micrometer or smaller. Because of their tiny size, they can pass through biological barriers in the body.
Recent research has detected these particles in human blood, lungs, and even the placenta. While the full scope of their impact on human health is still under investigation, early studies suggest they may disrupt the gut microbiome, trigger inflammation, or carry harmful chemical additives into the body.
In regions like Southern California, residents already face environmental challenges, as people in southern California breathe high levels of plastic chemicals every day, making any reduction in total exposure valuable. Similarly, while innovations like infinite recycling aim to break through plastic waste management issues at the source, simple home interventions provide an immediate defense for individuals.
What you can do about it
This research empowers you to take immediate action to improve your water quality without buying expensive devices.
- Check your water hardness: Look up your local water quality report or use a simple home test strip to see if you have hard water. If you do, the boiling method will be highly effective for you.
- Adopt the boil-and-filter routine: Consider boiling your drinking water in the morning, letting it cool, and filtering it into a glass pitcher for the day.
- Stay informed: Follow updates on plastic pollution and health. While boiling helps, reducing your use of single-use plastics remains the best way to lower the overall load on the environment.
- Consult professionals: If you are concerned about contaminants in your water beyond plastics, such as heavy metals or bacteria, discuss testing and filtration options with a water quality expert.
Sources & related information
ACS Publications – Drinking Boiled Tap Water Reduces Human Intake of Nanoplastics and Microplastics – 2024
This study by Zhanjun Li and Eddy Zeng presents the experimental evidence that boiling hard water encapsulates polystyrene, polyethylene, and polypropylene particles in calcium carbonate, allowing for their removal via simple filtration.
ScienceAlert – There’s a Surprisingly Easy Way to Remove Microplastics From Drinking Water – 2024
This article summarizes the findings of the Guangzhou Medical University team, explaining how the incrustant mechanism works and highlighting the difference in efficacy between hard and soft water samples.
Yale Environment 360 – Boiling, Filtering Water Can Get Rid of Microplastics, Study Finds – 2024
This report discusses the broader context of the study, noting that microplastics are found from the bottom of the sea to the clouds, and reinforcing that this low-tech solution could meaningfully reduce human consumption of plastics.
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