First the basics of ecobalancing are briefly explained. In this connection the main focus is set on material flow networks. In the software tool Umberto®, material flow networks are used to model material flows, which are necessary for creation of inventory analysis. Furthermore, data defects in material flow networks are classified, and causes and consequences of these data defects are pointed out. Afterward, possible solutions with their benefits and drawbacks are proposed. A case study (life-cycle assessment of a coating material) shows both data defects and some solution attempts. Finally a short outlook outlines some other approaches, which should be investigated in future work.