Cambérène area, part of Dakar city (Senegal) provided the opportunity to establish and analyze the full costs of a conventional system (sewer and waste water treatment plant) and the chain of Faecal Sludge Management in a low income country context and at scale. Indeed, this area is served by two sanitation systems: about 250 000 residents are connected to a conventional sewer and activated sludge reactor, while another 160 000 use on-site facilities like septic tanks, whose contents are collected by emptying trucks and treated on drying beds. The result is that the sewer system in Cambérène area is prohibitively expensive and cannot meet the needs of the population without huge external funding. According to this field assessment and in the conditions of Dakar, on-site sanitation systems with appropriate FSM however offer a technically and financially feasible alternative. On this point, there is an important market for mechanical pit-emptying in Dakar, and the FS treatment is finally not so expensive compared to the transport (1). Faecal Sludge Management appears to be an adapted option according the ability to pay of a large part of the population. However, it has also been observed in the same city that a part of the population – and probably the poorest – still turned to manual emptier for the maintenance of their pit (2). Dakar provides an interesting opportunity for negotiations build on a large donor-supported programme to expand access to sanitation for poorer households in Dakar.