In recent publications it is questioned whether the existing wastewater management system is suitable for future requirements. The today’s wastewater infrastructure is a complex socio-technical system characterized by centralization, very long life-spans and sunk costs. Thus, it appears questionable whether this system is suitable against the background of a context of dynamic conditions as demographic change, climate change and the emerging requirements in terms of sustainability. This paper adds a contribution to the growing body of literature on prospective waste water management systems. Focusing on long term developments this paper aims to build up scenario-modules towards the year 2050. Our approach combines three methodologies which appear to be suitable with each other, namely the method of explorative scenario development, a modified Delphi method and content analysis. As the waste water sector is a very complex system with various impact factors which are characterized by high dynamics and strong uncertainty the scenario technique appears as an appropriate method. Within the scenario building process a modified Delphi method had been applied to generate the input for the scenario-modules. Key drivers and uncertainties in the field of waste water management were identified by interviewing 16 experts who are scientists or practitioners in the waste water sector. The interviews had been transliterated and then evaluated by using the content analysis approach. Afterwards scenario-modules were derived which provide a basis for further procedure towards complete scenarios for future wastewater infrastructure.

In recent publications it is questioned whether the existing wastewater management system is suitable for future requirements. The today’s wastewater infrastructure is a complex socio-technical system characterized by centralization, very long life-spans and sunk costs. Thus, it appears questionable whether this system is suitable against the background of a context of dynamic conditions as demographic change, climate change and the emerging requirements in terms of sustainability. This paper adds a contribution to the growing body of literature on prospective waste water management systems. Focusing on long term developments this paper aims to build up scenario-modules towards the year 2050. Our approach combines three methodologies which appear to be suitable with each other, namely the method of explorative scenario development, a modified Delphi method and content analysis. As the waste water sector is a very complex system with various impact factors which are characterized by high dynamics and strong uncertainty the scenario technique appears as an appropriate method. Within the scenario building process a modified Delphi method had been applied to generate the input for the scenario-modules. Key drivers and uncertainties in the field of waste water management were identified by interviewing 16 experts who are scientists or practitioners in the waste water sector. The interviews had been transliterated and then evaluated by using the content analysis approach. Afterwards scenario-modules were derived which provide a basis for further procedure towards complete scenarios for future wastewater infrastructure.