On my old Jayco, there was an overflow tube under the tank near the rear. I noticed that water would come out of the tube when traveling so I took a wire nut, little plastic thing, and put it into the tube and that stopped the water from coming out. Had to remember to take it out when camping as it kind of set up a little vacuum that slowed down my water delivery until I took it out. Haven't noticed this with out Jayco HT 26.5 RLS yet, but we generally don't tow full of fresh water, prefer to fill up at the campgrounds and haven'g boondocked yet.