I carry a 6' length of 1/2" clear plastic tubing from the local hardware store. I bought a coupler to put in one end. When I am done with it, I roll it up and stick the other end on the coupler as well. That way, no water or junk can possibly get in the tube. I don't have a foot valve but with the clear tube you can see the gas coming so you can quit siphoning before you get a mouthful of gas!
It worked great last year when my sister got to the trailhead with two empty sleds. Of course we didn't figure that out until about ten miles from the truck! She had filled the sleds the night before and during the night someone stole all her gas!