In this paper, the water hammer phenomenon in a pipeline is simulated using the full Reynolds-Averaged Navier-Stokes equations. The flow is considered to be compressible and the effect of pipe elasticity is taken into account by introducing the bulk modulus of elasticity in the solution procedure. Computations are performed both for laminar and turbulent flows. The high-Re RNG k-ε and the low-Re k-ω SST turbulence models are employed for turbulence modeling. Numerical results for both laminar and turbulent flows are compared with the available experimental data and numerical results in the literature. For the laminar flow test case, the head variation shows good agreement with the experimental data. Comparisons for turbulent test case show that the RNG k-ε model somewhat over-predicts the head variation. The low-Re k-ω SST model, in the other hand, produces more accurate wall shear stress distribution than the high-Re RNG k-ε model. This highlights the importance of implementation of low-Re turbulence models for the prediction of water hammer flows.