You will most likely find your water pump near the point where you connect the city water hose, but hidden in an inside compartment. Look for a door that has three hinges on it. Remove the lone hinge where a latch would be more appropriate and you'll either find the water pump and filter or the water heater. If water heater, look for the other three hinged door
In my trailer the water pump is located behind one of these doors in the bathroom, below the tall closet door. My other door is hidden behind the pantry door at the bottom.
Floor plans vary but the clue will be where your city water inlet is on the outside. Close behind that will be the pump.