RV water pumps can be located by one of two ways. First, attempt to listen for the pump while its motor is running.
Secondly, locate the fresh water fill inlet on the outside of the RV. The pumps are usually positioned between the fresh water tank and that inlet, most likely behind an interior trim panel. Your Outback has a similar floor plan as my Bullet and your FW fill is in the same location.
So, I'm pretty sure it's located next to the left side of the queen bed (when facing front) behind the bedside table. In front of the clothes chute if you have one. There are 5 or 6 square head screws to removed from the top panel.