The main objective of the SMaRT-OnlineWDN project is the development of an online security management toolkit for water distribution networks that is based on sensor measurements of water quality as well as water quantity. Pseudo-real time modelling of water quantity and water quality variables are the cornerstone of the project. Existing transport model tools are not adapted for online modelling and ignore some important phenomena that may be dominant when looking at the network in greater detail with an observation time of several minutes. The aim of this deliverable is to define which phenomena should be considered in the online models. Firstly, existing models are described and the way water distribution networks are represented by graphs. Then, important phenomena that are missing are presented. The results are based on a bibliography study and the experience of the partners. Finally, a summary of conclusions is given. In summary, it is important to consider: 1)Inertia terms to make slow transient predictions of the hydraulic state. The velocity output will be slow-varying; 2)The hydrodynamic dispersion and possibly the molecular diffusion to improve the transport along a pipe and at junctions; 3)The imperfect mixing at Tee and Cross junctions depending on velocity inlets; 4)The diameter reduction and the wall roughness; It is proposed to calibrate these parameters on a regular basis (annual); 5)One chemical substance. It was also decided not to develop the model for 6)Pathogens; 7)Behaviour of multi-species; 8)Sedimentation. These are outside the scope of the project.