Interactions between urban forms and source-separating sanitation technologies

Up to now there is little experience regarding the retrofitting of source-separating sanitation technologies into existing housing stocks. This paper examines how specific characteristics of urban form can impact on the implementation of new sanitation technologies. A typology for residential areas in Germany was developed and exemplified in nine reference neighbourhoods in the city of Hamburg. The typology is based on physical characteristics like floor-space index, plot size and housing density. Four different source-separating sanitation systems were defined including urine separation and separate collection of black water in vacuum toilets. The suitability assessment of the four systems regarding their implementation into the different types of residential areas revealed that population density, housing layout and housing types are crucial factors. Also, possible impacts of socio-economic factors like family distribution or income are considered. As an example how urban form could affect investment costs, a cost assessment of the implementation of urine separation into the reference neighbourhoods was carried out. Housing density, population density and type of dwelling are factors influencing the specific investment costs. A reduced housing density results in increased demand for either pipes or storage containers making the implementation in less densely populated areas more costly.