After living in Bangladesh over the past two years to study childhood exposure to environmental contamination, this summer I returned on a Center for South Asia Summer Research Fellowship to pursue a new line of work: toilet engineering. Although I work in the PoopGroup, a Stanford research group that focuses on better understanding and addressing the issues of water, sanitation, and hygiene in low-income countries, I never thought that I would end up in toilet design—but anything is possible at Stanford! Supported by funding from the Stanford Institute for Innovation in Developing Economies, our project goal was to investigate the critical design features of an aspirational container-based toilet to serve individuals who use water (instead of toilet paper) for cleansing themselves after defecation.
A container-based toilet is one that accumulated toilet waste in containers so that the containers can be frequently collected and the waste properly treated off-site. Container-based sanitation is one option for fecal sludge management, particularly useful in communities where fecal sludge otherwise enters the environment untreated. Household container-based toilets can also provide cleanliness, privacy, security, and 24/7 access that may be lacking at shared latrine facilities. Of the container-based sanitation systems that are operated by Sanergy and Sanivation in Kenya, Clean Team in Ghana, SOIL in Haiti, and x-runner in Peru, most have designed toilets that separate the solid waste from the liquid waste, and collect and compost the solid waste as a treatment solution. The currently available container-based toilets are suitable only for people use toilet paper after they defecate—this summer we set out to design a container-based toilet for people in Bangladesh, where individuals squat while using the toilet and use almost 2 L of water for cleansing themselves after defecation. The design challenge is to devise a system that will separate liquids from solids in a user-friendly manner that requires little behavior change; the engineering challenge is to treat all of the liquid waste before it is discharged at the site of the toilet.
We started by meeting with local sanitation organizations to better understand the landscape of sanitation options and fecal sludge management practices in the community. To learn more about individual practices and preferences, we then held four focus group discussions and twelve individual in-depth interviews with women and men. We sent detailed notes back to our team at Stanford, who were busy designing and fabricating the toilet that our product designer brought over a few weeks later. Three households agreed to test our toilet prototype and provided valuable feedback on design elements that they did and did not like, made suggestions for improvements, and shared with us unexpected challenges such as the difficulty of washing the toilet and handling the negative perceptions of some neighbors. Despite the prototype breaking several times and the liquid disposal system not working as planned, they continued to open their doors to us so we could tinker and ask questions. I am impressed and grateful for the generosity of time that members of the pilot households and surrounding community, and the staff of local sanitation organizations, devoted to answering our many questions. They were patient with my poor Bengali and willing to put up with our design changes and fixes that involved tubes and tubes of superglue, even providing tea and biscuits as we worked.
According to the feedback we received in Bangladesh this summer, we are now revising our design to better meet user needs and preferences. We look forward to returning to Bangladesh to test an improved toilet, one that has the potential to be part of a container-based sanitation system which supports health by keeping untreated waste out of the environment.