Sustainability of Simplified Sewer systems

The universal access to safely managed sanitation remains one of the challenges to achieving the UN SDG target 6.2 in unplanned urban settlements including the Vingunguti area in Dar es Salaam City which is high-density populated. In an attempt to address this challenge, a simplified sewer system was piloted as an option for achieving safely managed sanitation in this particular area. The objective of this study was to assess the sustainability of the piloted simplified sewer system for its potentiality to up-scale and replication in areas with similar sanitation challenges in the country. Methodology involved collection of data on performance of different components of the sanitation service chain in the study area; and determination of sustainability index using a set of indicators. Data collection techniques included literature reviews, household questionnaires, expert surveys, and physical observations. Data analysis utilized the analytical hierarchy process (AHP) to assign weights to sustainability indicators, while the urban sanitation status index (USSI) was used to evaluate the status of the sanitation service chain, and the sanitation sustainability index (SSI) determined the level of sustainability of the sewerage system. Results showed that the emptying and transport component of the sanitation service chain performed better, with a USSI value of 0.905. However, the system performed poorly on the complementary services (stormwater, greywater, and solid waste management), which had a USSI value of 0.552, probably due to fewer investments in these services. On the other hand, the sustainability of the simplified sewer system was found to be high, with an SSI score of 76.5%. Hence, the study concludes that, simplified sewer system is an appropriate option for addressing safely managed sanitation in unplanned urban settlements where connection to conventional sewer systems is challenging. Thus, the system in Vingunguti area can be up-scaled and replicated elsewhere with similar conditions in the country.