Unfortunately, that is not unusual. Every single RV floorplan has the water pump located in a different spot. Someone would have to be very familiar with that particular model in order to know where the water pump is. For example, we have about 150 different floorplans on our dealership's lot; that's mean I would have to remember where the water pump is located for 150 different models.
What I usually tell folks is to turn the water pump on and allow it run (either with pumping water or just air) and then listen for it. It can be located underneath a kitchen cabinet, inside a storage compartment behind a panel, under the bed, etc. Sometimes you'll have to remove some sort of access panel to get to it.
Casey
1995 K1500 Tahoe 2 door, 6.5LTD, 4L80E, NP241, 3.42's, 285/75R16 BFG K02's; 1997 506 block; Kennedy OPS harness, gauges, Quick Heat plugs, and TD-Max chip; Dtech FSD on FSD Cooler; vacuum pump deleted, HX35 turbo, Turbo Master, 3.5" Kennedy exhaust, F code intake; dual t/stats, HO water pump, Champion radiator; Racor fuel filter