A two phase water hammer has been simulated with Method of Characteristics (MOC) and Computational Fluid Dynamics (CFD). MOC is performed in 1D with the Discrete Vapour Cavity Model (DVCM) and the Discrete Gas Cavity Model (DGCM). The CFD model is performed in 2D with an axisymmetric pipe. MOC and CFD are compared with 4 different experiments found from literature, which covers a range of different dimensions and flow conditions. The Rayleigh-Plesset equation was investigated with the purpose of implementation in MOC, but because of time step size complications and time limitations, this did not succeed. DGCM was found as the overall best two phase water hammer model, as it gave an accurate estimation of the pressure, robustness with large void fractions, and an accurate estimation of the timing of the oscillation.