A compliance assessment tool for household pit latrines and cesspits against RS ISO 24521: evidence from Kigali City

Introduction: On-site sanitation systems (OSS) are the primary sanitation technology used to manage household fecal sludge in the Global South, including Kigali City. Poor quality OSS can lead to the spread of fecal-oral diseases and water resource pollution. Previous studies have demonstrated that OSS in Kigali are ineffective. In 2018, the Rwanda Standards Board adopted ISO 24521 to guide the design, construction, and management of domestic OSS. However, limited evidence exists on the compliance of OSS with the established guidelines, and no established tools are currently available to assess such compliance. This study developed and tested an assessment tool to evaluate the compliance of households' pit latrines and cesspits against RS ISO 24521 and identify factors associated with compliance. The study further proposes recommendations for enhanced compliance coverage and safe sanitation services in Kigali. Methods: The tool was tested through a survey of 903 households in five sectors of Gasabo District in Kigali, through facility inspection, questions, and observations. Data were analyzed using descriptive statistics, Generalized Linear Mixed Model, and Rao-Scott chi-squares. Within RS ISO 24521, four standard objectives were covered: (i) Protection of Public Health, (ii) Meeting Needs and Expectations of Users, (iii) Sustainability, and (iv) Protection of Environment. Results: The results show that full compliance with the four standard objectives was 0.5, 4.8, 0.4 and 3.4% for pit latrines, and 79.2, 11, 0.4 and 2% for cesspits. Technical awareness and hygiene behavioral factors were found to be associated with low compliance. Both pit latrines and cesspits showed very low full compliance with the Sustainability objective, which in turn precluded examination of any associations to full compliance for this objective. For characteristics included in Protection of Public Health, factors such as wealth, house tenure, and residence type showed significant associations. Discussion and conclusion: To address the low compliance with selected objectives of RS ISO24521, recommendations emphasize increased enforcement of regulations, sanitary inspections, promotion of hygiene behavior change, and sustainable water supply. By evaluating the assessment tool, an improved version is proposed to support the management of OSS in Kigali, as well as in other cities with rapid urban growth and high reliance on OSS.