Sanitation: When Toilets Fly
Photo credit: Felipe Jacome
Sanitation: When Toilets Fly
Initiative run by Stanford graduate students aims for a dry solution to sanitation challenges in urban slums where untreated sewage in waterways spreads disease This story is part of a series about Stanford researchers developing solutions to water supply and access challenges that affect billions of people.
Initiative run by Stanford graduate students aims for a dry solution to sanitation challenges in urban slums where untreated sewage in waterways spreads disease
This story is part of a series about Stanford researchers developing solutions to water supply and access challenges that affect billions of people.
Kory Russel had an epiphany in an outhouse.
Russel, now a graduate student in civil and environmental engineering at Stanford, was a Peace Corps volunteer in Mozambique in 2006. His bathroom was a small outhouse built over an open pit latrine. In cool weather, cockroaches would swarm up from the depths, and mass into a swarming ball. “It was disturbing,” Russel recalled. The experience got Russel thinking about how he had taken for granted access to piped water for sanitation and other uses.
Around the world, 2.5 billion people lack access to adequate sanitation. In many of the world’s overcrowded urban slums, residents must choose crowded public toilets, open defecation, or expensive private pit latrines that can't be emptied safely.
To offer an alternative, Russel and fellow civil and environmental engineering graduate student Sebastien Tilmans co-founded an initiative called re.source. Under the guidance of Associate Professor of Civil and Environmental Engineering Jenna Davis, the Stanford team is developing portable, affordable dry household toilets and entrepreneurial service models for the developing world. Davis has a dual appointment as Higgins-Magid senior fellow at the Stanford Woods Institute.
"The goal is to isolate feces from people,” Russel said. “Then we neutralize that waste so it's not a hazard anymore, but actually a valuable product."
Russel and Tilmans developed the re.source toilet in the field through a partnership with Sustainable Organic Integrated Livelihoods (SOIL), a Haiti-based nongovernmental organization co-founded and directed by Sasha Kramer, Ph.D. ‘06.
The re.source toilets separate solid and liquid waste into sealable containers, and dispense a cover material made of crushed peanut shells and sugarcane fibers that eliminates odors and insect infestations. The solid waste is regularly removed by SOIL staff, who take it to a disposal or processing site to be converted to compost and sold to agricultural businesses. Customers can subscribe to the toilet service for a monthly fee of 5 USD – less than 3 percent of average monthly expenditures for households in a re.source study in Cap Haitien, Haiti – and they can take their toilet with them when they move. Mobile tracking technology monitors waste collectors' performance, maximizes efficiency and minimizes service costs.
“Sanitation is so much more than a fancy toilet,” Tilmans said. Most sanitation solutions only address one part of a dysfunctional supply chain. Container-based sanitation models, such as the re.source service, tackle the whole sanitation chain, from capturing waste in the home to removing it safely from the community and turning it from a hazardous material into a valuable product.
From Watery Mess to Dry Solution
About two-thirds of Haiti’s 5.3 million urban residents lack access to basic sanitation services. In Shada, a Cap-Haitien slum, many people use toilets with septic systems or pit latrines. These options, often in the form of shared communal or public facilities, are generally closed at night, subject to flooding during storms, and cannot be emptied safely because narrow, unplanned street layouts make access by suction trucks impossible. Frequent floods send human waste floating into homes, and people commonly dispose of their feces in plastic bags known as flying toilets or hélicoptères that they throw into waterways. As a result, waterborne diseases such as cholera are a constant threat.
Working with the Water, Health and Development program of the Stanford Woods Institute, Tilmans and Russel have tested multiple toilet models with users, including a free pilot phase with 130 households in Shada. Early iterations had ventilation issues, didn’t hold up to Haiti’s intense humidity, and required frequent patch jobs in the field. “It was a miserable, smelly, ugly situation,” Russel said.
When they finally got the toilet design right, it caught on. Of the households that used the service for the three-month pilot phase, 87 percent described themselves as “very” or “generally” satisfied, according to research led by Russel, and scheduled for publication this fall.
Since then, re.source has used the insights from this research to advise SOIL, which has expanded the service to about 2,500 customers in more than 300 paying households, and started a second service in Haiti’s capital, Port-au-Prince.
The Way Forward
The success has not gone unnoticed. In 2014, re.source won a $15,000 grant from the U.S. Environmental Protection Agency (EPA) and the opportunity to compete for a $75,000 grant this April at the EPA National Sustainable Design Expo in Washington.
To design the toilet, understand users’ needs and aspirations, develop effective outreach initiatives and interface with government authorities, Russel and Tilmans have turned to Stanford faculty, students and alumni with expertise in engineering, anthropology, education, policy and planning. “Sanitation is an inherently interdisciplinary challenge,” Tilmans said.
A viable business plan is key to bringing down costs and scaling up the effort. With higher demand, large corporations will likely compete to market dry toilet systems. To that end, Russel and Tilmans – both fellows in the Stanford Woods Institute’s Rising Environmental Leaders Program – are consulting with entrepreneur Ashish Jhina, MBA ‘11, and building partnerships beyond Haiti, in Kenya and Peru, among other countries. “For this to really be a game-changer, you need to start serving people on the scale of hundreds of thousands,” Russel said.
Support for re.source has come from the Stanford Woods Institute, the Stanford Institute for Innovating in Developing Economies, the Bill and Melinda Gates Foundation and the U.S. Environmental Protection Agency.
- In Kenya, Senegal and Colombia, Stanford researchers are looking at how to design sanitation service improvements that are safe, reliable and affordable in the long-term, and quickly achieve impact at a large scale. Read more…
- In Panama, Stanford researchers are working to quantify the value of biogas as a way to convert wastewater to energy in relation to the costs of building and operating rural wastewater treatment systems. Read more…
- In Mozambique, Stanford researchers are quantifying the impacts of a rural water project on time devoted to water collection, income generation/poverty, school enrollment and health. Read more…
- In Bolivia, Peru, India, Ghana and elsewhere, Stanford engineers are looking at institutional challenges such as corruption and mismanagement that hinder adequate sanitation and water delivery. Read more…