Assessment of Sanitation Infrastructure Resilience to Extreme Rainfall and Flooding: Evidence from an Informal Settlement in Kenya

Abstract

Sanitation infrastructure can fail during heavy rainfall and flooding, allowing the release of fecal waste – and the pathogens it carries – into spaces where people live, work, and play. Within the unique context of informal settlements, there is a scarcity of reliable indices that can effectively assess the resilience of such infrastructure to extreme wet weather events. The purpose of this study was to develop and apply a novel index for assessing and ranking the resilience of sanitation infrastructure in informal communities. Data were collected from 200 shared sanitation facilities in Kibera, Kenya, through transect walks, field observations, surveys, and sanitary risk inspections. Scale development resulted in a 19-item index categorized into four domains: physical infrastructure design (5 items), the functionality of infrastructure (8 items), routine operations and management (4 items), and environmental factors (2 items). The study found a significant association between the level of resilience and the type of sanitation infrastructure. Toilet facilities connected to a piped sewer (r = 1.345, 95% CI: 1.19—1.50) and toilets connected to a septic system (r = 1.014, 95% CI: 0.78—1.25) demonstrated higher levels of resilience compared to latrines (r = 0.663, 95% CI: 0.36—0.97) and hanging toilets (r = 0.014, 95% CI: -0.30—0.33) on a resilience index scale ranging from 0 to 4. The key determinants of sanitation infrastructure resilience were physical design, functionality, operational and maintenance routines, and environmental factors. This evidence provides valuable insights for developing standards and guidelines for the safe siting of new sanitation infrastructure and encourages investment in sewer and septic systems as superior options for resilient sanitation infrastructure. Additionally, our findings underscore the importance for implementers and communities to prioritize repairing damaged infrastructure, sealing potential discharge points into open drains, and emptying filled containment systems before the onset of the rainy season.

Keywords: Sustainable sanitation, urban sanitation, on-site sanitation systems, Climate Change, extreme weather events