Modeling the flow dynamics of leaks in water pipe networks is an extremely difficult problem due to the complex entangled network structure and hydraulic phenomenon. A mathematical model for leak dynamics in water pipe networks based on consensus algorithm and water hammer theory is proposed. The resulting model is a simple and linearly interconnected system even though the dynamics of water pipe networks has considerable complexity. The model is then validated using experimental data obtained from real pipe network. A comparative study demonstrates the proposed model can describe the real system with high qualitative and quantitative accuracy and it can be used to develop model-based leak detection and location algorithm based on state estimation. To show applicability of the proposed model, we apply cooperative  estimation to the developed model. The results demonstrate the consensus-based pipe model can be potentially used for leak detection and location with state estimation.