Well, I haven't hauled anything but it did rain like crazy overnight. I checked this morning and had a little water inside the bed but not too much. It was on the driver side near the cab of the truck. I'm not sure where it was coming in from, but I was parked up a slight incline with the rear end higher than the front...oh, and I haven't installed the drain tubes yet either. I figured I'd see how things go before I did that. I know some folks on here have passed on installing them too. If I continue to see water inside, I might give them a shot. I do like the cover though, love that it sits flush and that i can open and close the tailgate with the cover down all the way.