Where is the evidence? A global systematic review of sanitation system resilience to climate hazards

Abstract

Despite sustained efforts over several decades, no region is projected to achieve universal sanitation access by 2030, according to international monitoring frameworks. Climate change is increasingly disrupting human and ecological systems, in turn deepening existing inequalities in access to essential services, including sanitation. Coupled with broader socio-economic and political dynamics, these pressures are expected to further widen the global sanitation service gap. Strengthening the resilience of sanitation systems to climate-related impacts represents a critical component of addressing this challenge. Building resilience requires an understanding of the attributes of sanitation systems and the adaptation actions across scales that contribute to their capacity to anticipate, withstand and recover from climate hazards. While existing scholarship has primarily examined the impacts of climate hazards on sanitation system performance, less attention has been given to resilience-building processes and practices. This systematic review is the first to synthesise the evidence on resilience in sanitation systems. The review identifies twenty-seven (n = 27) attributes and adaptation actions with potential to enhance resilience, none of which are currently considered in existing global monitoring processes. Only seventeen (n = 17) studies met the inclusion criteria, and empirical evidence remains scarce, highlighting substantial knowledge gaps. Findings also reveal a dominance of user-level, infrastructure focussed actions in low-income settings, with minimal evidence on operational or enabling environment strategies implemented by service providers or government actors. These findings highlight a substantial gap between identifying potential resilience-building measures and demonstrating how they contribute to resilience sanitation systems. Strengthening the evidence base requires greater emphasis on evaluating resilience outcomes, understanding interactions across the sanitation system, and examining how institutional and operational conditions shape adaptation over time. The findings provide a foundation for developing measurable indicators of climate resilience while highlighting the need for further empirical evidence to inform international monitoring frameworks and guide effective climate resilient sanitation planning.