Scientists from the University of Auckland have made a groundbreaking discovery, finding that harakeke (New Zealand flax) could be a powerful tool in the fight against water contamination. Early experiments show the native plant’s fibres can successfully remove the vast majority of harmful ‘forever chemicals’ from water, offering a potential sustainable solution to a growing environmental problem.
The breakthrough was sparked not in a high-tech laboratory, but at a local school event. Professor David Barker, a chemical scientist at the university, was helping children with harakeke weaving when a Māori parent mentioned the plant’s traditional use for cleaning water. While its roots are known to purify water as it grows, Professor Barker began to wonder if the leaves themselves held similar properties.
“Its different chemical properties just seem to be a good match for the harakeke,” says Professor Barker. His initial curiosity led to a series of tests, which have now evolved into a dedicated research project with remarkable results.
The science behind the solution
The research, now driven by PhD student Shailja Data, focuses on perfluoroalkyl and polyfluoroalkyl substances, better known as PFAS. These are dubbed 'forever chemicals' because their molecular structure is so stable they do not naturally degrade in the environment, allowing them to accumulate over time.
PFAS are used to create non-stick and water-resistant coatings on everything from cookware and raincoats to food packaging and cosmetics. While not acutely toxic in small doses, prolonged exposure has been linked to immune system deficiencies and other health issues. In response to these concerns, New Zealand will ban forever chemicals in cosmetic products from the end of 2026.
The Auckland University team developed a method to treat harakeke fibres, giving them a positive charge. When these treated fibres are shaken in contaminated water, they attract and bind with the negatively charged PFAS molecules. The process has proven highly effective, removing between 70 to 99 per cent of the chemicals from water samples.
The very same properties that make PFAS good [for manufacturing] mean it’s not good for the environment or human health, it can keep building up until it’s at a harmful level.
A focus on emerging threats
A significant aspect of the research is its effectiveness against short-chain PFAS. These are newer variations of the chemicals, often introduced as ‘regrettable substitutions’ for older, longer-chain PFAS that have been phased out by regulators. According to Ms Data, these smaller molecules are notoriously difficult to remove from water with existing filtration technologies.
“Most PFAS treatment has been developed for traditional, longer PFAS, so treating short-chain PFAS in drinking water supplies around the world is an important public health issue,” she says. The harakeke fibre’s natural rigidity makes it ideal for water immersion without disintegrating or creating secondary pollution like microplastics, which can be a risk with synthetic filters.
While testing has shown relatively low levels of PFAS in New Zealand’s waterways to date, the chemicals are a persistent and growing threat. They enter the environment as consumer and industrial products break down, eventually seeping into groundwater and drinking water supplies. The cost of upgrading water treatment plants to handle such contaminants is a major challenge for councils, with the Hutt City Council recently proposing a lower rates rise amid widespread cost pressures on infrastructure.
From lab to large-scale application
One of the most promising features of the harakeke method is its potential for reuse. After the fibres have captured the PFAS, they can be washed with a solvent. This removes the chemicals in a concentrated form, which can then be safely destroyed by breaking their strong carbon-fluorine bonds. The clean fibres can then be used again, creating a sustainable and long-lasting filtration cycle.
However, the team acknowledges there is a long road ahead before this technology could be implemented at a commercial scale. The initial experiments have been conducted under controlled lab conditions, and more work is needed to see how the fibres perform in real-world scenarios.
“In the real world, there are different variables, different ions, more organic matter,” Ms Data says. “It would be exciting to understand how it performs.” Further research is also needed to understand the full scope of PFAS exposure in New Zealand, including in kaimoana and agriculture, as international data may not apply to the local environment, similar to how monitoring volcanic activity at Whakaari/White Island requires specific local expertise.
A marriage of science and mātauranga Māori
Professor Barker credits mātauranga Māori as the foundational inspiration for the project, highlighting the deep, centuries-old connection between Māori and the native plant. Harakeke is a taonga, or treasured, species, and its fibres, known as muka, have long been used to create kete (baskets), cloaks, and fishing traps.
“Working with Māori researchers, I’ve understood how deep the connections with the plants are,” Professor Barker says. This project is a modern example of how traditional knowledge can inform contemporary scientific innovation, a principle that values a holistic understanding of the natural world. This link between cultural heritage and learning is seen elsewhere in the community, with facilities like the Walter Nash Centre offering free guidance for family history searches, connecting people with their past.
The project joins a growing movement to find modern applications for harakeke. Local companies like Kiwifibre are already using it to create replacements for carbon-fibre, while Biotenax is developing yarns to substitute for synthetic textiles. This research adds water purification to the plant’s expanding portfolio of potential uses.
Professor Barker says there is significant interest from farmers, small companies, and iwi in growing harakeke as a commercial crop, which could foster a regenerative and uniquely New Zealand industry. “We wanted to use fibres available locally so that if projects were successful then potentially we could develop locally,” he says. Ultimately, finding effective ways to remove persistent pollutants is essential. “Having materials that can remove pollutants is critical for all our health,” Professor Barker says.
