Or, don't even remove the drain valve. On the eXtreme, the drain valve is about the perfect size to squeeze a piece of 3/8 clear vinyl tubing through. Push the tubing through the drain hole from the outside and hose clamp the braid to the tubing (I put a short little piece of copper tubing (from an old sink feeder line) into the end of the tubing so I could tighten the clamp as hard as I wanted to without collapsing the tubing, but that's probably not really necessary). If you want, you can add a little aquarium sealant where the tubing goes through the drain hole but lots of folks report that's not necessary either. You can then add an inline valve to the tubing outside the cooler or, like I do, just raise the end of the tubing to shut off flow and lower the end when you want to drain.