Liquid gold: Research highlights potential – and risks – of turning human urine into sustainable fertilizer

A new research review led by Griffith University suggests using human urine as a fertiliser could significantly boost sustainable agriculture – but key health risks and knowledge gaps must be addressed before it could be widely adopted.

The 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 while urine was a highly efficient source of nutrients – containing up to 80 per cent of nitrogen and 50 per cent 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 gastrointestinal 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 storing urine could reduce many pathogens through a natural process called urea hydrolysis, which produced ammonia and helped kill pathogens.

However, the effectiveness of this process varied 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.

"Our review also highlighted emerging concerns around antibiotics and antimicrobial resistance,” co-author Professor Cara Beal said.

“Residual pharmaceuticals in urine were not consistently removed during treatment and may contribute to the spread of antibiotic-resistant bacteria.

“While studies suggest minimal uptake of these substances in crops, they may still move through soil and into water systems.”

Despite these 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.