Microplastics in Tap Water: New Discoveries on Removal

About a decade ago, the notion that tiny microplastic particles could be present in our tap water seemed far-fetched. It felt more fitting for a science fiction story than an everyday conversation. However, tests conducted globally have revealed countless nano- and microplastic flecks lurking in the water we use.

The effects these particles have on the human body are still being studied, but it’s safe to say that no one wants plastic at their dinner table.

Could it really be this easy?

Researchers Zhanjun Li and Eddy Zeng, along with their team from Guangzhou, China, have discovered a surprisingly straightforward method to eliminate up to 90% of these microplastics from boiling tap water, thanks to the minerals found in hard water.

As it turns out, boiling water, a common practice for making coffee or formula, can remove a significant portion of these invisible threats.

This revelation emerged from a study aimed at addressing the idea that such a massive problem might be too daunting for individuals to confront on their own.

Microplastics and Boiling Water

When water containing calcium is heated beyond 212°F, the minerals start to crystallize into flakes of calcium carbonate. This process results in the same chalky residue that can often be found in well-used kettles.

In the study, these newly formed flakes floated through the heated water, binding to free-floating microplastics and pulling them down to settle at the bottom of the pot.

Tests on three types of common resins — polystyrene, polyethylene, and polypropylene — indicated that over 80% of these particles ended up trapped after just five minutes of boiling followed by a brief cool-down period. This percentage soared close to 90% when the water contained about 300 milligrams of calcium carbonate per liter, which is a typical level in hard-water areas like San Antonio and Indianapolis.

Why Minerals Matter

Water chemistry can vary greatly across the U.S. In soft water, where calcium levels fall below around 60 milligrams per liter, the same Guangzhou team noted a 25% reduction in plastic particles. While useful, that still allows a lot to remain.

Conversely, hard water offers more calcium, giving rise to more surfaces for plastic to attach to, thus increasing removal rates significantly.

As these flakes develop quickly, they can easily be rinsed or scrubbed away from pots and pans while taking the microplastics with them. Additionally, any particles that remain suspended in the water can be filtered out using a paper coffee filter, which many people have on hand.

This method is inexpensive, requires no electrical equipment apart from the burner, and is ideal for homes that might not have the space or budget for advanced filtration systems.

Evidence Outside the Lab

The notion that simple heating can mitigate hidden plastics aligns with recent field studies. In 2025, researchers examining bottled and tap water across Europe found anywhere from 19 to 1,154 microplastic particles per liter, with the highest counts appearing in municipal supplies sourced from mineral-rich aquifers.

By leveraging these same minerals, the boiling technique serves as a temporary solution while lawmakers consider tougher water standards.

Health organizations like the World Health Organization mention that current data doesn’t firmly link microplastic ingestion to specific diseases, although reducing exposure where feasible is encouraged.

The U.S. Geological Survey echoes this sentiment, advocating for easy measures that individuals can adopt now.

Tips for the Kitchen

If your kettle tends to accumulate residue between cleanings, you’re likely to see the most benefits. Just bring the water to a rolling boil for five minutes, then allow it to cool until the steam dissipates, slowly pouring it out while leaving the white crust behind.

Regularly cleaning the kettle will help wash away any captured plastics, as municipal treatment facilities are better suited to handle larger, bonded particles than the tiny ones.

Residents in softer-water regions can still achieve a modest reduction by adding food-grade calcium, like a small amount of pharmaceutical lime, before boiling.

However, it’s important that any mineral additives remain within the U.S. Environmental Protection Agency’s (EPA) secondary limit of 120 milligrams per liter for calcium to avoid any taste issues.

Boiling Water vs. Microplastics

While boiling water is not a complete solution, engineers are working on bio-based filters designed to capture plastic fragments in wastewater treatment plants, and chemists are researching enzymes that could break down plastics into harmless compounds.

Nonetheless, the findings from the Guangzhou study highlight how an age-old method can help combat a contemporary pollutant without the need for high-tech tools.

Simply utilizing stovetop heat alongside an inexpensive paper filter can significantly reduce the amounts of microplastics entering our beverages, even while the scientific community seeks long-term solutions.

Plastic pollution won’t disappear overnight, but this study serves as a reminder that sometimes, solutions are hiding in plain sight.

The complete findings were published in the journal Environmental Science and Technology Letters.