Xylem technology measures water quality during epic swim on the Danube River

In April 2022, Andreas Fath began a 57-day journey, in which he would swim 2,700 kilometers (1,678 miles) to raise awareness of pollution in the Danube River. As he swam through 10 countries, his team used Xylem’s portable meter to take daily measurements of temperature, turbidity, pH, conductivity, and dissolved oxygen. Here’s their story.

Starting in Germany’s Black Forest, the Danube is a bustling thoroughfare for shipping and a tranquil refuge for summer holidays. As Europe’s second-largest river, it’s an important source of hydropower and a haven for fish, birds, and amphibians.

The Danube River also washes four metric tons of microplastics a day into the Black Sea. For the CleanDanube project, one of Fath’s most urgent messages is that pollution in the world’s rivers is likely to increase.

“As the climate changes, we have strong rainfalls,” says the 57-year-old chemist. “With these strong rainfalls, everything around us is released into the water,” he explains. Evidence of the pollutants becomes clear when floodwaters recede.”

“You can see only the tip of the iceberg,” Fath says. “The rest of the plastic pollution is delivered to the sea. Nine million [metric] tons every year are released to our oceans. Rivers are the deliverers of pollution.”

A passion for swimming and preventing pollution

Andreas Fath, known as “the Swimming Professor,” has found a unique way to combine his passion for swimming with his commitment to battling pollution in the world's rivers. He has been a competitive swimmer since 1973, worked for two decades as an industrial chemist, and joined Germany’s Furtwangen University in 2011 to teach chemical process engineering and environmental chemistry.

In 2014, Fath swam the entire length of the Rhine in 28 days to generate publicity about pollution. Along the way, he sampled water quality and shared his results, such as the microplastics he found at the very start of the river in the alpine snowfields of Switzerland.

“Even at 2,340 meters, you find microplastics,” Fath says. “Nobody lives there. There is no industry, no cars. You're in the middle of nowhere. It was a shock.”

In 2017, Fath received a call from an American professor about his Rhine River data that resulted in a new friendship and a 34-day swim down the Tennessee River. He and his friend Martin Knoll of Sewanee University used the swim to inspire cleanups and anti-pollution legislation in the American South.

Swimming from the Black Forest to the Black Sea

On April 19, 2022, Fath started his Danube swim in a neoprene suit to protect him from the chill of 9.5°C (49°F) water. The Danube drops almost immediately underground into a network of limestone caves in Germany's Black Forest.

The next day, Fath squeezed through underground passages 85 meters below ground to swim in the subterranean river – nicknamed the Black Danube – before it reemerged to feed Lake Constance.

His swim along the Danube was closely supported by a team of seven professionals who handled everything from publicity to education, water sampling, safety, and logistics. The team included Edgar – the captain of the MS Marbach, which served as a floating home base and research vessel – filmmaker Shane McMillan, and Mario Kümmel of the Association for Wildlife Protection, who acted as a logistician and publicist.

Graduate students Tim Kiefer and Felix Broghammer sampled water quality all along the way, while students from Berlin, Sarah Regier and Lukas Seubert, conducted educational workshops when Fath stepped on shore.

Along the route, swimmers, kayakers, and boaters joined Fath for sections of his journey. On shore, reporters, dignitaries, fans, and hundreds of children greeted his arrival at stops.

“There is no place where I left the water without litter around me – bottles and bags,” Fath says. In most parts of the river, his team found that microplastic particles outnumbered aquatic organisms.

Measuring water quality and educating the public

Graduate students Kiefer and Broghammer used three different filtration methods to capture microplastic particles along the route to analyze with an infrared spectrometer. They also used a multi-parameter portable meter, Xylem’s WTW MultiSet 3630, to take daily measurements of temperature, turbidity, pH, conductivity, and dissolved oxygen.

Fath wore passive sampling membranes on his legs to pick up persistent organic pollutants along his travels. Just as important as the sampling instruments in the water, Fath made skillful use of the most important tool on dry land: the microphone.

“We used our media presence to talk to people, to talk to politicians,” Fath says.

In addition to meeting with the ministers of the environment of both Slovakia and Austria, he shared the spotlight with local non-governmental organizations (NGOs) in the countries he visited.

“They are visible now – more visible than before – because of the CleanDanube project,” Fath says. “The media came, and I did interviews, but the NGO leaders did interviews, too, along with us. It's a multiplication effect.”

Fath notes that the biggest media splash occurred in Belgrade, where he refused to swim a murky, brown 15-km (9.3-mi) stretch where the city dumps raw sewage into the river. The plummeting dissolved oxygen levels in the water running through Belgrade were dramatic to see. But so was the attention the CleanDanube project focused on local clean water activists.

“That was amazing – the biggest media response we had, ever,” he says. "Every day, I got phone calls from journalists. The NGOs and activists there had a lot more power to talk than before.”

Inspiring river cleanups on the Rhine and Danube

“The Swimming Professor” now has three river journeys under the belt of his swim trunks. Through his trips down the Danube, Rhine and Tennessee River, Fath has inspired cleanup efforts. For the past four years, people have joined in an international, one-day cleanup effort along the Rhine. Like Fath’s swims, RhineCleanUp is a logistical feat and a labor of love on a grand scale.

On September 10, 2022, 40,000 people lined the Rhine and several of its tributaries to collect trash – 300 metric tons of it. The same day, 25 groups of residents along the Danube conducted a cleanup of their own. Fath is convinced that people who spend a day pulling trash out of their river are changed forever, more aware of where their garbage goes and unlikely to contribute to pollution.

“You can read the river and see what people use for medicine, how they treat their waste,” Fath says. “Rivers are a mirror of society.”

Read the full story and more

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Written by Steve Werblow