Contextualising urban sanitation solutions through complex systems thinking: A case study of the South African sanitation system

South Africa's urban sanitation infrastructure is unfit-for-purpose and collapsing, leading to significant environmental and health risks. Many alternative sanitation solutions exist, but their implementation has not produced successful roll-out to scale in this context. These failures are likely due to many interactive, systemic factors. This research adopts a transdisciplinary knowledge synthesis approach to map the possible systemic factors to provide engineers and policymakers with relevant information to identify contextual risk factors for potential failure and emerging problems and novel approaches. Building from the narrative literature reviews and the joint fact-finding approach, the sustainable systems-of-systems framework is used as the analysis tool to identify important elements of the complex systemic context. The output is a set of nine interweaved contextual constraints. The value of the contextual constraints is illustrated by application to three commonly implemented sanitation solutions (chemical toilets, urine-diverting dry toilets, and decentralised wastewater treatment systems) where relevant contextual components of the success (or failure) of the solutions are highlighted. The framework is not intended to replace existing linear-thinking decision-making tools, but to provide important contextual information to augment existing decision-making. •Sustainable urban sanitation solutions require complex systemic thinking.•Transdisciplinary perspectives frame the boundary conditions for solutions.•Systems-of-systems framing allows the identification of novel, emergent solutions.•Identifying complex contextual constraints is critical to success.