This High School Student Invented a Filter That Eliminates 96 Percent of Microplastics From Drinking Water
Virginia teenager Mia Heller’s filtration system harnesses the power of ferrofluid, a magnetic oil that binds to microplastics in flowing water
A few years ago, teenager Mia Heller came across an article in her local newspaper about ongoing water quality issues in her neighborhood in Warrington, Virginia. Tests had revealed that the water available for daily consumption was highly contaminated with PFAS and microplastic pollution. The article further reported that government agencies would not be providing any funds for filtering the water.
“It was up to people to provide their own filtration,” says Heller.
Not long after the article came out, Heller’s parents invested in an advanced water filtration system at her home. The system, however, required constant upkeep. Seeing her mother replace the water filter membranes time and again, Heller set out to find a better solution.
“It inspired me to design a filter without the use of membranes, to decrease the costs and maintenance needs associated with water filtration,” says the now 18-year-old student at Kettle Run High School. Through her school, she also attends a half-day program for math, science and technology at nearby Mountain Vista Governor’s School.
The pervasiveness of microplastics
The Environmental Protection Agency defines microplastics as small particles measuring about 1 nanometer to 5 millimeters in size. These tiny particles pose a growing global concern as they infiltrate not just the environment but also humans and animals.
“Micro- and nanoplastics are getting into our bodies,” says Matthew J. Campen, a toxicologist at the University of New Mexico in Albuquerque. A recent study revealed that microplastics have been found in 1,300 species, including humans. So far, these pollutants have been detected throughout the human body, from the brain to the insides of bones; concentrations have also been found in testes, semen and the placenta of unborn fetuses.
Microplastic intake by organisms has increased sixfold since 1990, and plastic production continues to grow. A 2025 University of New Mexico study Campen co-authored revealed that concentrations of microplastics found in human brain tissue have increased by a sharp 50 percent in less than a decade.
“There are still a lot of questions as to whether these plastics are really impacting our health at this point,” says Campen, who also studies the effects of complex inhaled pollutant mixtures on respiratory, cardiac and vascular outcomes. He goes on to note the existence of evidence that “there might be issues for cardiovascular disease and potentially neurological disease.” The links, however, are not strong enough to be conclusive.
Though the exact impacts of microplastic consumption on human health are unclear, a number of recent studies have linked it to adverse health issues like cancers, respiratory and cardiac diseases, hormonal disruptions, Alzheimer’s disease and other noncommunicable diseases.
Quick fact: What's the difference between primary and secondary microplastics?
- According to the EPA, primary microplastics are tiny plastics manufactured for things like cosmetics and biomedical products. Secondary microplastics are plastic pieces that have broken down from larger plastic consumer products.
A new take on water filtration
While several water filtration systems are available, they aren’t all efficient and easily accessible to everyone. Traditional systems often rely primarily on chemical treatments and may also require labor-intensive upkeep and frequent membrane changes. They also come with high price tags and maintenance costs.
In the spring of 2024, Heller had the idea for her filtration system, but she really got working on it in the summer of 2025. By early January of that year, after tinkering in her garage and kitchen, she had a working prototype.
“It was essentially just a container,” she says. Within the container was her filtration system, what she called a “spinning magnified vial.” Heller harnessed a reusable magnetic oil called ferrofluid to selectively bind to microplastic particles as water flows through her filtration system. While her model successfully filtered out the microplastics from the water in two simple steps, the system still required constant maintenance, as it did not self-recycle the ferrofluid.
“But if I could create a system that was able to basically clean itself and reuse material," she explains, “the maintenance needs could go down by a lot.”
Determined to find an answer, Heller continued experimenting. One of the main obstacles she faced was figuring out how to place her units so that the ferrofluid—a liquid thicker than water—would be able to move into the water chamber above it without getting clogged. Along with the ferrofluid flow, the process of magnetic separation followed by the recovery of ferrofluid also needed to work together as one system rather than competing with each other.
About five iterations later, she found the perfect solution. Her current prototype, which is about the size of a standard bag of flour, consists of three modules. The first unit, about a liter in volume, holds the contaminated water inside it, while the second stores the magnetic oil-based ferrofluid. The core process takes place in the third module, which is much smaller. “A magnetic field pulls the microplastics out of the water, and the ferrofluid is recovered and reused in a closed loop,” explains Heller. As a stand-alone filter (similar to a Brita pitcher), the system can filter about one liter of water at a time.
Next, to test the accuracy of her device, she developed a turbidity sensor, which measures the amount of suspended solids in a liquid. She used the sensor to precisely gauge the amount of ferrofluid and microplastics in the water. The sensor also calculated the weight-based percentage of microplastics removed by her filter. According to her tests, her prototype successfully removed 95.52 percent of microplastics from the water and recycled 87.15 percent of the ferrofluid. Traditional drinking-water treatment plants remove about 70 to more than 90 percent of microplastic components.
“The result is an affordable, low-waste filtration system without the use of a solid membrane,” says Heller.
Her innovation has garnered some well-deserved accolades. Heller was a finalist in the 2025 Regeneron International Science and Engineering Fair, the world’s largest global science competition for high school students. There, she was presented with a special $500 award by the Patent and Trademark Office Society for her innovative, low-cost and efficient water filtration technology.
Is it scalable?
Campen is excited about Heller’s filtration system and considers it a “really great idea.” He adds, “She is doing something that has to be done.” And considering that her recent test results are just a starting point for a high school research project, he continues, one can only imagine that those percentages would improve with a little bit of investment in innovative engineering.
The toxicologist still has some valid concerns. “We have to know that the way she extracts these microplastics captures them in a way that we can then discard them or destroy them in a way that gets rid of them completely,” he says. The system, he adds, shouldn’t “leave some other pollutant residue that we have to deal with.” Assuming it does remove the microplastic components without leaving any residues, then the next question, he explains, is whether it’s scalable.
Campen wonders about the best application for Heller’s device. Would it be most effective installed in individual plumbing systems or, on a bigger scale, placed directly at municipal water treatment plants?
Heller considers it suitable as an at-home under-the-sink filtration system. “Because ferrofluid is currently expensive to produce at a large scale,” she notes, “I see this as a system for individual home use.”
But Heller plans to take things one step at a time, and for now, would simply like to professionally confirm the results she found at home.
“I would love to eventually bring it out to market,” she says. “I think that would be something that would be really interesting.”
