Linda, if your Ventura is a relatively short model like ours, the pump compartment others mention can be on the curbside, rather than next to the wet bay. Ours is in the main bay with the slide tray, behind a pop-out panel in the left wall. It is here that you go to pump antifreeze through your water system when winterizing. The pump complex is in a plastic box that extends into the adjoining bay where the waste tanks, Alladin modules, and bay heat exchanger is, so the pump is adequately kept from damage when camping in freezing weather.
Related to that, it is common for new owners to not realize there is a waste tank bay access door on our models, with unobvious latches hidden underneath the front edge. The bay is in front of the curbside rear wheels.
The most common factory configuration, as others note above, is just one filter- an icemaker one within the pump complex box. Additionally, the owners manuals are frequently universal, and any one specific instruction may or may not apply to your particular coach, and could be for an option your rig never had.
Joel