It started with a local water problem and a lot of filter changes at home. For Mia Heller, that turned into a high school research project aimed at pulling microplastics out of drinking water without using a membrane.

A few years ago, Heller read an article in her local newspaper about water quality issues in her neighborhood in Warrington, Virginia. Tests had found that the water available for daily consumption was highly contaminated with PFAS and microplastic pollution. The article also reported that government agencies would not be providing funds for filtering the water.

“It was up to people to provide their own filtration,” says Heller, according to Smithsonian Magazine.

After that article was published, Heller’s parents bought an advanced water filtration system for their home. But the system needed constant upkeep. Heller watched her mother replace the water filter membranes again and again, and started looking for another option.

“It inspired me to design a filter without the use of membranes, to decrease the costs and maintenance needs associated with water filtration,” Heller tells Smithsonian Magazine, now 18 and a 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.

Microplastics are a growing concern. The Environmental Protection Agency defines them as small particles measuring about 1 nanometer to 5 millimeters in size. The agency says primary microplastics are tiny plastics manufactured for products such as cosmetics and biomedical products. Secondary microplastics are pieces that have broken down from larger plastic consumer products.

These particles are turning up in the environment, animals and people. “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 found microplastics in 1,300 species, including humans. Researchers have detected them 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 rise. A 2025 University of New Mexico study co-authored by Campen found that concentrations of microplastics in human brain tissue increased by 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,” Campen says. He adds that there is evidence that “there might be issues for cardiovascular disease and potentially neurological disease.” He says the links are not strong enough to be conclusive.

Recent studies have linked microplastic consumption to cancers, respiratory and cardiac diseases, hormonal disruptions, Alzheimer’s disease and other noncommunicable diseases, though the exact impacts on human health remain unclear.

Heller came up with the idea for her filtration system in the spring of 2024 and began working on it in the summer of 2025. By early January of that year, after experimenting in her garage and kitchen, she had a working prototype.

“It was essentially just a container,” she says.

Inside it was what she called a “spinning magnified vial.” Heller used a reusable magnetic oil called ferrofluid to selectively bind to microplastic particles as water moved through the filter. Her early model removed microplastics in two steps, but it still needed constant maintenance because it did not recycle the ferrofluid on its own.

“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.”

She kept refining the design. One of the biggest challenges was arranging the units so the ferrofluid, which is thicker than water, could move into the water chamber above it without clogging. She also needed magnetic separation and ferrofluid recovery to work together as one system instead of competing with each other.

After about five more iterations, Heller says she found the answer. Her current prototype is about the size of a standard bag of flour and has three modules. The first unit, about 1 liter in volume, holds the contaminated water. The second stores the magnetic oil-based ferrofluid. The third, and much smaller module, is where the main process happens.

“A magnetic field pulls the microplastics out of the water, and the ferrofluid is recovered and reused in a closed loop,” explains Heller.

Used as a stand-alone filter, similar to a Brita pitcher, the system can filter about 1 liter of water at a time.

To test the device, Heller developed a turbidity sensor to measure the amount of suspended solids in a liquid. She used it to measure the amount of ferrofluid and microplastics in the water, and to calculate the weight-based percentage of microplastics removed.

According to her tests, the prototype 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 project made her a finalist in the 2025 Regeneron International Science and Engineering Fair, described as the world’s largest global science competition for high school students. There, she received a special $500 award from the Patent and Trademark Office Society for her low-cost and efficient water filtration technology.

Campen called the filtration system a “really great idea.” He added, “She is doing something that has to be done.”

He also said the test results are an early step for a high school research project and could improve with investment in engineering. Still, he has concerns about what happens after the microplastics are removed.

“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, should not “leave some other pollutant residue that we have to deal with.”

If the system removes microplastic components without leaving residues, Campen says the next question is scale. He wonders if the device would work best in individual plumbing systems or at municipal water treatment plants.

Heller sees it as an under-the-sink system for homes. “Because ferrofluid is currently expensive to produce at a large scale,” she notes, “I see this as a system for individual home use.”

For now, she wants 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.”