During 2016, numerous incidents leading to public health issues were reported by users in the city of Port-Louis. Studies have shown an essential difficulty, namely the saturation of old individual sanitation systems (fosses and sumps) in the area concerned. These people are located in the centre of Port-Louis, an area classified as collective sanitation. Indeed, the parcels of these dwellings are too small and do not allow the rehabilitation of individual wastewater treatment systems. Work is therefore needed for the construction of a collection network for these dwellings, prior to 2007 for the transport to the Lalanne treatment plant. Thus creating a wastewater network at Rue Guy TIROLIEN, territory of the city of Port-Louis, is the solution for the removal of this situation of public unsanitary.