VANCOUVER — The term “wonderful experience” isn't often used to describe a trip to the toilet, but researchers at the University of British Columbia say the description fits their waterless mushroom-powered toilet.
It is described as the world's first such toilet, turning human waste into compost using mycelium, the root network of fungi. MycoToilet, located inside a small cedar-walled building, was installed among the trees of the university botanical garden for a six-week test run.
In the toilet, liquid is separated from solids and solid waste enters a mycelium-lined compartment where laboratory tests have shown that 90 percent of odor-causing compounds are absorbed.
Stephen Hallam, a professor in the university's department of microbiology and immunology, said they have long known that tree roots contain certain fungi that help trees absorb nutrients and protect them from pathogens.
“We learned that a breathable mycelial shell can reduce odor while removing residual moisture, limiting the occurrence of anaerobic conditions and creating more favorable conditions for aerobic decomposition,” Hallam said.
The modular toilet requires only four maintenance visits per year. Once operational, it is expected to produce approximately 600 liters of soil and 2,000 liters of liquid fertilizer per year.
Joseph Dahmen, project leader and associate professor at UBC's school of architecture, said composting toilets “stand out in people's minds because of the odor associated with them.”
He said they looked into materials for their restroom that could not only create a sustainable way to “green the campus” but also reduce odor.
“We really wanted to use this design to recontextualize an activity that we often take for granted and do without thinking, to kind of put it in a new light and suggest that a toilet with a waste separator doesn't have to be some kind of sacrifice in order to use it,” Dahmen said.
“But it can be a really beautiful experience that connects us to natural ecology.”
Dahmen said one user even compared the toilet to a Scandinavian sauna.
Prefabricated timber panels form the structure, there is a skylight at the top, and a green roof supports native plants. A low power fan keeps the air circulating, and there is a ramp leading to the entrance.
Hallam said the facility is a “living laboratory” as researchers will evaluate the liner's performance over time to understand how using different mushrooms might affect circulation.
He said they will evaluate the effectiveness of the mushroom liner over the six weeks it is in the garden, using a combination of analytical and DNA barcoding techniques to better understand some of the issues, including pathogen load.
“So everyone who uses this toilet is also effectively doing citizen science,” Hallam said.
“We hope that the entire liner can be turned into usable compost, supporting native plant life within the botanic garden and beyond,” Hallam added.
Dahmen said that during his classes he asked students what happens to their waste after flushing, most of them did not know the answer.
“While current wastewater treatment infrastructure plays an important role in our society, it ultimately results in liquid wastewater ending up in rivers and streams after treatment,” Dahmen said.
“It's probably time to rethink some of them with a new conceptual framework so that we treat them not as waste, but as a source of nutrients that are valuable and can contribute to local ecosystems,” Dahmen said.
Hallam agreed that large wastewater treatment plants aren't going away anytime soon, but there is a movement in the wastewater community to rethink the concept of a waste resource recovery system.
“Waste is a function of our values, and if we can rethink what we value in that context, there will be a lot of useful material in that wastewater and we can recover that, then we will add value again and create a more circular model for the economy and our lives,” Hallam said.
This summer, the World Health Organization released a report on drinking water and sanitation showing that 3.4 billion people still lack access to safely managed sanitation.
“Despite progress over the past decade, billions of people around the world still lack access to basic water, sanitation and hygiene services, putting them at risk of disease and deeper social exclusion,” the WHO said in a statement.
Dahmen said they also hope that similar toilets will be used in low-income countries to meet their sanitation needs.
This report by The Canadian Press was first published Oct. 12, 2025.
