© 2003-2012 IEEE. Considering the fact that the Euclidian Minimum Spanning Tree (EMST) is a subset of the correspondent Delaunays triangulation, this paper presents a novel algorithm for designing a UDWDM PON based on the selection of an optimal tree-topology from a Voronoy-Delaunay tessellation in the users region. Additionally, we employ not only restrictions related with the fiber length and equipment capacity but also restrictions related with the physical impairments in the optical fiber due to the UDWDM technique. For modeling the UDWDM-related physical restriction, we developed a mathematical expression for evaluating the BER-penalty as a function of the channels and links aggregation. The results show that, due to the BER-penalty imposed by the UDWDM transmission, in this type of networks any optimization scheme must take into account the channels aggregation in the optical links.