This paper presents an analytical investigation of water hammer pressure variation in a reservoir-pipe-valve system. Laplace transform method is used to get the analytical solutions for different characteristics of the valve closing. Specifically, sudden valve closing and piecewise linear closing are used, the latter can be treated as approximated arbitrary characteristics of valve closing. Unsteady wall friction is also included. The new solutions compare well with the previous experimental data. The results show that this solution is suitable for water hammer with laminar and low Reynolds number turbulent unsteady flow. The effects of different characteristics of the valve closing on the water hammer pressure variations are also studied. This solution can be a better choice for optimization of valve closing to reduce the maximum water hammer pressure.