Artificial runoff experiments revealed high share of macropores and, thus, preferential flow in vegeted filter strip (VFS) soils. These are most likely due to higher organismal activity, e.g., earthworm channels. They cause a rapid transport of parts of the surface runoff to subsoil layers, but may also cause a complete bypass of VFS. Accordingly, the type and extent of flow pathways needs to be acknowledged and accounted for in VFS designs.