By Abbas Nazil
In a breakthrough that could offer a simple household solution to the growing problem of microplastic contamination, chemists in Guangzhou, China, have discovered that boiling hard tap water can eliminate up to 90% of microplastics.
The study, led by researchers Zhanjun Li and Eddy Zeng, found that when water rich in calcium is heated, minerals naturally present in the water crystallize and bond with plastic particles, dragging them out of suspension.
This discovery presents a low-cost, accessible method to significantly reduce microplastic exposure in drinking water, particularly in regions with hard water.
When calcium levels reach around 300 milligrams per liter—a concentration common in many U.S. cities like San Antonio and Indianapolis—boiling water for five minutes was found to trap the majority of microplastics such as polystyrene, polyethylene, and polypropylene.
As the water cools, the mineral flakes, known as calcium carbonate, form a chalky residue that can be discarded, along with the attached microplastics.
Although the World Health Organization and the U.S. Geological Survey maintain that the health effects of microplastics are not yet fully understood, both agencies advocate reducing exposure wherever feasible.
This boiling method aligns with that goal, offering a practical intervention for households that may lack advanced filtration systems.
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Even in soft water, where calcium content is below 60 milligrams per liter, the study observed a 25% reduction in plastic particles.
The researchers suggest that in such areas, adding small amounts of food-grade calcium—such as pharmaceutical lime—before boiling can boost effectiveness.
However, they caution users not to exceed the EPA’s secondary calcium limit of 120 milligrams per liter to avoid affecting water taste.
The results also support previous field studies indicating that areas with mineral-rich aquifers tend to show higher microplastic levels in tap water.
While more advanced solutions such as enzyme-based plastic degradation and wastewater filters are being developed, this study underscores how everyday practices like boiling water can provide immediate relief.
To implement the method, users are advised to boil water for five minutes, allow it to cool, and pour slowly to leave the mineral crust behind.
The remaining flakes can be cleaned from kettles and discarded. Additionally, paper coffee filters can help capture any lingering fragments.
Though not a comprehensive solution, this method represents a practical step in reducing daily microplastic intake using tools most households already own.
