As Bumpyroad mentioned, it is not unusual at all to not have a gravity fill. While my prior rig, a 2002 Cedar Creek, had one, my current rig, a 2008 Jayco Designer does not. While surprised and disconcerted at first, it's turned out to be not such a big issue. If I need to put water in the tank when attached to city water pressure, I simply set the control panel to tank fill. If I need to put some water in from a 5 gallon jug, I set it in the winterize mode which sucks water out of the jug. The only 'complaint' that that I have is the amount of time it takes to fill an 80 gallon tank via the smaller pex lines. Was faster with a gravity fill.