This paper summarizes the problems caused for wastewater systems by changing wastewater composition, especially the increasing use of nonwoven wet wipes and their disposal via the toilet. The nonwoven wet wipes do not disintegrate in the sewer system as paper-based toilet does, but accumulate to large agglomerations that can block the system and clog pumps. This not only reduces the operational safety and stability of the wastewater system, but also costs the operator a lot of money. The paper introduces an approach to estimate the composition of wastewater and presents first results for the city of Berlin.