There are many different varieties of barrel cactus, but a couple of things pretty much hold true with all of them. First, the taller ones tend to point toward the south. This is due to the fact that for most of the year the sun is more toward the south. Second, it is not a good idea to drink the juice from the cactus when out of water. A couple of reasons for that; one, these cacti are tough, and the perspiration expended to open one of these up would exceed the available water within. Secondly, the liquid will most likely cause a horrible case of diarrhea, further depleting the body of water and accelerating dehydration.