A recent review, led by a multi-disciplinary research team from Griffith, analysed 35 global studies examining microbial risks associated with urine-derived fertilisers (UDF).
With growing pressure on global food systems and fertiliser supply chains, urine recycling represented a promising – but still developing – solution for more sustainable agriculture, off-grid communities and water-scarce regions for use in spaces such as private gardens or public-use areas.
Such technologies have been piloted in Australia and several countries, including Switzerland, Germany and New Zealand.
For example, VUNA (Valorisation of Urine Nutrients in Africa) was an implementation project aimed at developing an improved sanitation system enabling complete nutrient recovery from urine.
The urine-based fertiliser derived from this project, Aurin, received official approval in Switzerland, however, the project encountered challenges in expanding its scale due to scale, collection, community awareness, and acceptance.
The team found that while urine was a highly efficient source of nutrients, containing up to 80% of nitrogen and 50% of phosphorus in wastewater, its safe reuse remained uncertain.
Doctoral researcher Johanna Engels said the biggest risk was not urine itself, but contamination from faecal matter during collection and storage. This cross-contamination could introduce harmful pathogens capable of causing illness.
“Urine has enormous potential as a renewable fertiliser, but our review shows we don’t yet fully understand the health risks,” Ms Engel said.
The study found that storing urine could reduce the danger through a natural process called urea hydrolysis, which produces ammonia and helps kill pathogens.
However, the effectiveness of this process varies widely depending on environmental conditions such as temperature, pH and dilution with water – making it difficult to control in real-world settings.
The research team also warned viruses – likely present but rarely studied – may persist longer than bacteria, meaning current risk assessments could underestimate potential health impacts.
Despite challenges, the research highlighted the strong potential for urine reuse to support circular economy goals.
“By recovering nutrients from waste streams, urine-derived fertilisers could reduce reliance on energy-intensive synthetic fertilisers and help address global resource shortages,” said Associate Professor Md Sayed Iftekhar, the ARC NiCE Hub Griffith Node Lead.
However, the authors stressed further research was essential before the practice could be scaled, including exploring better data on pathogen levels, improved treatment methods, and standardised safety guidelines.
“Addressing these uncertainties is critical to building public confidence and enabling safe, large-scale use,” Associate Professor Iftekhar said.
The review ‘The potential health risks of stored urine used as fertilizer– what evidence do we have?’ has been published in Water Reuse.