Several computer tools exist for Water Distribution Systems Analysis. The most well known of which Epanet will not be maintained in the near future. To remedy this, open source development projects have recently been proposed. Cemagref have developed the Porteau software, with several tools. They have decided to make their software open and freely available. In this paper, we present our experience to design a hydraulic toolkit for Water Distribution Analysis which could benefit the community in the context of an open-source project. Firstly, technology choices are explained and highlighted in the current context. Some key elements were the objectives of a multiplatform product, the graph library availability and computation performance. Then, the main results in terms of packages and classes are presented. Graph elements consist of nodes, links and hydraulic devices. A collection of hydraulic devices/equipments may be placed at different locations on a pipe. Different classes with distinct attributes and methods have been created for the nodal and link demands as well as for the local and background leakages. Finally, the calculation targets are described with an example of extension ease with pressure-driven modelling and a reliability measure.