There is a need for water distribution network models to better assess water quality for safety and security in case of contamination intrusion. One critical enhancement needed is to take into account imperfect mixing at junctions. This paper completes previous work by conducting LES and DNS CFD calculation and laboratory experiments. Statistics were compiled on large-size networks in France and Germany to serve to design a test rig and supply CFD cases for the numerical simulation. The main influencing factors were identified to be: the inter-Tee distance and three of the Reynolds numbers of the inlets/outlets. A lookup table and interpolation methods are used to model inside a one-dimensional model. This is implemented in the transport module of Porteau software.