There is not much different between the water jet and this WJB during handle pushing to shot out the water. The main different is during user reload the water into the water jet or this WJB.
For water jet, the user needs to find a water source. Then the nozzle must put down and fully immersed inside the water (if not the user will suck the air only). Then pull the handle to suck the water into this water jet.
While for user using this WJB, his/her job is only to pull the handle of this WJB, regardless of the current WJB water jet position. Then the water from the backpack tank will refill into its water jet. That is the user job only push or pull this handle, go wherever he/she like and the fun continue, as long as there is water inside this backpack tank.
The WJB having two built in check valves to control the water push out from the water jet and water suck in from the backpack tank when user pulling the handle.
The pushing mechanism is as shown in Fig. 3 below.