Recently, as global-scale problems, such as global warming and energy depletion, have attracted attention, the importance of future environmental preservation has been emphasized worldwide, and various measures have been proposed and implemented. This study focuses on water hammer pumps that can effectively use the water hammer phenomenon and allow fluid transport without drive sources, such as electric motors. An understanding of operating conditions of water hammer pumps and an evaluation of their basic hydrodynamic characteristics are significant for determining whether they can be widely used as an energy-saving device in the future. However, conventional studies have not described the pump performance in terms of pump head and flow rate, common measures indicating the performance of pumps. As a first stage for the understanding of water hammer pump performance in comparison to the characteristics of typical turbo pumps, the previous study focused on understanding the basic hydrodynamic characteristics of water hammer pumps and experimentally examined how the hydrodynamic characteristics were affected by the inner diameters of the drive and lift pipes and the angle of the drive pipe. This paper suggests the effect of the air volume in the air chamber that affects the hydrodynamic characteristics and operating conditions of the water hammer pump.