Combining proven technology: an innovative water solution to remove fluoride

“Too much fluoride in water can cause brown teeth and other health issues. In Kenya’s Rift Valley, people live with that reality every day.” Begüm Tanis and Guus Wiersma from TU Delft explain how they are working on a practical water solution to provide safe drinking water: a household water filter designed to tackle both excess fluoride and bacterial contamination. Supported by the Partners for Water programme, the project aims to improve water security while reducing costs and plastic waste.

Wiersma, project coordinator, and Tanis, assistant professor, both work at TU Delft’s Water Management Department. They are part of a consortium comprising Harbauer Limited, Resilience BV, Nazava Water Filters Ltd., and Delft University of Technology. Their shared goal? Safe, affordable drinking water—without the environmental cost.

Synergising proven water solutions

“The two components of the solution are both already existing technologies,” explains Wiersma. “We combined Nazava’s ceramic filter, which is highly effective at removing bacteria and viruses, with the HAPaqua system.” The latter is an adsorbent filter designed to reduce fluoride levels, using Hydroxyapatite as its base material.

Tanis adds: “The system operates with granular material through which the water flows, allowing the fluoride to bind to the granules. As the water passes through the filter, the fluoride is captured by the material, resulting in water with significantly reduced fluoride content.”

Addressing a critical health concern

The project targets Kenya’s Rift Valley, where naturally occurring fluoride in the groundwater often exceeds safe levels. “Most people in the region are aware that consuming too much fluoride can lead to health problems, such as brown or mottled teeth—also known as dental fluorosis,” explains Wiersma.
Tanis adds: “In the past, many residents relied on bone char (charcoal made from animal bones) to filter out fluoride. But this method has several drawbacks, including health concerns, inconsistent quality, and limited filtration capacity.”

“The impact on the daily lives of users will be significant,” says Wiersma. He shares that the initial response from the communities has been very open and positive.

Benefits beyond clean water

The filter can be used with various water sources, including rainwater, groundwater, and even surface water. However, the impact of this innovation goes beyond simply providing safe drinking water. “Currently, people buy bottled water when they can afford it. But with the Nazava filter, you can treat up to 7,000 litres of water,” Tanis explains. “That’s quite a lot.” “This saves households money by reducing the need to purchase expensive bottled water, but also significantly cuts down on plastic waste,” adds Wiersma.

Testing in real conditions

Rather than conducting tests in the Netherlands using artificially contaminated water, the team set up a laboratory in Nakuru, Kenya, to test the filters with naturally fluoridated water. “By testing on location, you get the most accurate results, because you’re using the actual water the filters are designed to treat,” explains Tanis.

The team collected water from two different boreholes, each with distinct fluoride concentrations. “We continuously used water from the same sources for each test, ensuring that the fluoride concentration in the inflow remained relatively constant,” Tanis adds. “This allowed us to reliably compare the performance of the filters under consistent conditions.”

The team also collaborated with Egerton University in Nakuru, where a local student joined the project as an intern. In addition, an undergraduate student from TU Delft spent several months in Kenya working with the prototypes and conducting water quality testing.

“It’s a great opportunity for students to work on applied, real-world projects,” says Wiersma. “The students supported us in testing two different prototypes and also conducted additional tests to examine preferential flow,” adds Tanis. “The outcomes of both the students’ tests and our tests were promising, showing that the filters effectively removed fluoride.”

Royal recognition

During a state visit to Kenya, Queen Máxima of the Netherlands and the Minister for Foreign Trade and Development Reinette Klever, were also introduced to the water solution. “Queen Máxima’s response was very positive,” says Wiersma enthusiastically. “It was great to show them our prototype. The Queen’s interest could help raise awareness of the fluoride contamination issues in the Rift Valley.”

Looking ahead: scaling for wider impact

The team has applied for the next round of Partners for Water funding to continue testing and improving the solution before scaling up. “Initially, we’ll focus on Kenya,” says Tanis, “but the Rift Valley stretches from Ethiopia through Kenya and Tanzania all the way down to Mozambique. People face the same issue throughout the region, so if you have a solution that works, why not scale it up?” Wiersma concludes: “Ultimately, our goal is to provide access to safe drinking water for everyone, while simultaneously reducing the plastic burden on the environment.”