Shit Flow Diagram

A shit flow diagram (SFD) is a visual tool that maps how human excreta moves through urban sanitation systems, distinguishing safely from unsafely managed flows with color-coded arrows whose widths represent the proportion of the population affected. It tracks containment, emptying, transport, treatment and disposal or reuse, highlighting leakages where waste is inadequately contained, untreated, or discharged to the environment. Developed and standardized through collaborations among international organizations (including SuSanA, GIZ, the World Bank, EAWAG and the Gates Foundation) and formalized by the SFD Promotion Initiative, the approach combines literature review, field observation, key-informant interviews and stakeholder workshops. Graphic-generation tools translate analyzed data into standardized diagrams and the methodology now includes assessing the enabling environment - policy, regulation and institutional capacity. Practical limitations arise from data gaps and technical constraints, prompting ongoing methodological refinement.

Applied SFDs reveal specific failures and priorities for investment: Babati, Tanzania, showed only 31% of fecal waste safely managed onsite and 69% unsafely discharged, prompting a shift away from premature sewer plans. Greater Kampala relies almost entirely on onsite systems (≈99%), with 53% of septic tanks never emptied and only ~35% of sludge reaching the Lubigi treatment plant. Alappuzha, India, reports universal toilet access but no treatment facilities, widespread E. coli contamination and eutrophication from seepage. In Guwahati seasonal flooding undermines otherwise "improved" systems, producing sanitation stacking and leaving roughly 46% of systems safely managing sludge. These diagnostics direct targeted interventions in fecal sludge management and treatment capacity.