Fish gill design removes 99% of microplastics from washing machine water

Every year, a four-person household's washing machine sheds about 500 grams of microplastics — tiny fibers from clothes breaking down with each spin cycle. These particles slip through standard filters, travel through sewage systems, and end up in farmland fertilizer and drinking water. They've been found in human blood, lung tissue, and the most remote corners of the planet.

Now researchers at Germany's University of Bonn have borrowed a solution from nature. By studying how fish like sardines and anchovies filter food from water, they've designed a washing machine filter that captures more than 99% of those microplastics without clogging.

How Fish Gills Became the Answer

Fish gills work like elegant cross-flow filtration systems. Water flows through funnel-shaped gill arches covered in tiny comb-like teeth that act as a natural sieve. Plankton too large to pass through rolls down toward the gullet where it collects until the fish swallows — a motion that automatically cleans the filter. Millions of years of evolution solved a problem that modern washing machines still struggle with: how to catch particles without getting blocked.

Biologist Leandra Hamann and her team realized existing washing machine filters either clog quickly or don't filter well enough. "Some of them quickly become clogged, others do not offer adequate filtration," Hamann explained. Rather than pursuing complex engineering, they looked to what fish had already perfected.

After testing different mesh sizes and funnel angles, the team created a filter that mimics the gill arch structure. Water flows through, microplastics get trapped, and the funnel shape keeps particles rolling toward a collection outlet instead of bunching up and blocking the system. The filter sucks out accumulated plastics multiple times per minute.

From Lab to Laundry Room

What makes this breakthrough practical is its simplicity. The filter requires no complex mechanical parts and costs very little to manufacture. Once microplastics are collected, a washing machine could press them to remove water, then mold them into a pellet. After a few dozen washes, you'd simply remove a small plastic block and throw it in the bin.

With a patent pending, the University of Bonn team is now working with washing machine manufacturers to integrate the design into commercial models. The shift from 500 grams of microplastics per household per year to nearly zero isn't just an engineering win — it's the kind of systemic change that keeps these particles out of soil, water, and bodies in the first place.

The next phase is turning a lab prototype into something in homes worldwide.