The article presents the results of experimental studies investigating the conditions during the filling and start-up of a water ram based on changes in pressure in the working zone and the pressure zone. The test stand is described, and measurements are conducted in three configurations: (a) when the system is filled with water (with the delivery pipe empty); (b) when the water ram is manually activated (with the delivery pipe empty) and (c) when the water ram is activated after a manually induced break in water supply (with the delivery pipe filled with water). The results of the study indicate that the operation of the ram pump will be automatically resumed in every configuration, provided that the delivery pipe is filled with water to the appropriate height. The aim of this study was to describe new applications for a water ram, in particular under varied supply conditions.