Economic cost analysis of low-cost sanitation technology options in informal settlement areas (case study: Soweto, Johannesburg)

Abstract

In Urban Africa, water and sanitation utility companies are facing a huge backlog of sanitation provision in the informal settlement areas. In order to clear this backlog, new investment is required. However, to select appropriate sanitation technologies, lifecycle costs need to be assessed. The aim of this research was to establish lifecycle costs for appropriate sanitation technologies in informal settlement areas. Three sanitation options were compared: simplified sewerage, urine diversion dry toilet (UDDT) and Ventilated Improved Pit (VIP) latrine. Three scenarios for simplified sewerage were considered; gravity flow into existing conventional sewers with treatment; new-build with pumping and treatment; and new-build gravity flow with treatment. The study revealed that simplified sewerage is the cheapest option for Soweto informal settlement, even when the costs of pumping and treatment are included. Gravity simplified sewerage with treatment is cheaper than the UDDT system and VIP latrine at all population densities above 158 and 172 persons/ha, respectively. The total annual cost per household of simplified sewerage and treatment was US$142 compared to US$156 and US$144 for UDDT and VIP latrine respectively. The costs of simplified sewerage could be recovered through a monthly household surcharge and cross-subsidy summing US$5.3 The study concluded that simplified sewerage system was the first choice for Soweto informal settlement areas, given the current population density.

Keywords: Economic costs; Financial costs; Lifecycle costs; Low-cost sanitation; Simplified sewerage system; Urine diversion dry toilet; VIP latrine.