Reinventing the Toilet

A waste treatment system designed for off-grid sanitation needs

Bill & Melinda Gates Foundation
Duke University, Colorado State University, NASA Ames Research Center, U.S. Naval Research Laboratory

Around the world, some 2.4 billion people lack access to toilets or improved sanitation, and more than 1 billion resort to open defecation—a practice that poses significant health and environmental risks.

Even in urban areas, more than 2 billion people live without services and infrastructure for the safe disposal of human waste, which can result in contaminated drinking water. Diarrhea caused by poor sanitation and unsafe water kills more than 300,000 children each year.

Turning Human Waste into Fuel and Disinfected Water

Under grants from the Bill & Melinda Gates Foundation’s “Reinvent the Toilet” challenge, in 2012 we assembled a team of experts to develop a novel waste treatment system designed for use in the places where people need it the most.

Since then, our team has made major progress—developing a bench-scale technology and advancing an integrated prototype for field testing in Ahmedabad, India.

The system is a closed loop, with technology to treat and reuse the liquids and generate power for the system through the combustion process. It’s designed to operate off-grid—without piped-in water, a sewer connection, or outside electricity—converting human waste into burnable fuel, stored energy, and disinfected, non-potable water.

And we are targeting an operating cost of less than US$ .05 per day.

Prototype Testing Gathers User Feedback and Key Cultural Insights

In 2014 we demonstrated our first prototype at the Reinvent the Toilet Fair India in New Delhi, where the response was overwhelmingly positive. Researchers and government officials found our approach exciting—specifically, how our system burns human solid waste, harvests energy from feces, and uses electrochemical disinfection rather than chemicals or additives. Participants in the Reinvent the Toilet Fair also saw tremendous value in the water savings achieved through low-flush volume and use of recycled disinfected liquid for flush water, as well as our team’s commitment to integrate menstrual hygiene management processes into the interface and process technology.

Following the demonstration, we conducted a 12-month field test of our alpha unit and in September 2016 began testing our beta prototype. The success of these field tests draws on our long-standing relationships with government agencies and leading NGOs, as well as urban planning experts at the CEPT University in Ahmedabad.

Prototype testing provided key insights from users on the technology and the design, along with feedback on our approach to on-site waste treatment. By testing the system in India, we also gained a valuable understanding of how our system must be managed in light of local use practices, weather, and environmental conditions.

Engaging Local Partners to Understand Social, Economic, and Cultural Perspectives

Our collaboration also includes other key partners:

  • The Self Employed Women’s Association (SEWA), who mobilized low-income community participants to engage in our user studies
  • NEERMAN, a Mumbai-based research and consulting organization that supported qualitative and quantitative data gathering
  • L&T Engineering, which conducts value engineering on the prototype and serves as operational support for the CEPT field test site
  • Public Health Foundation of India (PHFI), who provided our team with a health researcher specializing in health and cultural issues around menstrual hygiene management.

These partners were instrumental in helping us understand important social, economic, and cultural perspectives, and supported our engagement and conversations about the technology and approach in Hindi and Gujarati.

Testing Additional Prototypes in South Africa and India

In 2017, our team aims to deploy two additional prototypes to different use-case settings. In Durban, South Africa, we will test a prototype unit in a low-income urban community’s shared toilet, shower and washing stations—referred to as a community ablution block (CAB). In partnership with the University of KwaZulu Natal (UKZN) and the eThekwini Municipal Water Services (EWS) authority, we will demonstrate the application of our system in a public toilet setting to inform both technology and partnership development.

Similarly, in Coimbatore, in the southern Indian state of Tamil Nadu, we will partner with a spinning mill to test our prototype at the site of a female workers’ dormitory. This test site will also demonstrate the use of our system in a shared toilet setting and will also facilitate our efforts to incorporate women’s sanitation needs into the design.

In parallel, RTI is working with U.S. Army Natick Soldier Research, Development, and Engineering Center to develop a mobile version of our off-grid treatment system for forward-operating bases.

Improving Public and Environmental Health and Raising Quality of Life

Ultimately, our aim is to complete development of a waste treatment system that can be integrated into modern life in poor rural and urban communities. We are working to ensure it aligns with cultural norms and will be accepted and used by the people who need it most.

And in so doing, we hope our technology will support significant improvement in public health, the environment, and quality of life among people in developing nations around the world.