When studying urban drainage systems using techniques like hydrodynamic calculations, an overwhelming amount of data is produced and is to be interpreted. Additional information such as street plans, groundwater levels, full terrain models, etc., is very helpful in quickly determining the necessity of measures to be taken in case of flooding problems, for example. Moreover, when acquiring data and building a computer model for a given urban drainage network, it is laborious to eliminate data errors. ArcView GIS and ArcView 3D Analyst provide visualization techniques that enhance the data checking and interpretation of modeling results. Dynamic water flow through the sewer network as well as water levels in manholes can be visualized.