Water is a life critical substance, especially for the military. Any potable water they carry is to be used ONLY for drinking. If you want to wash yourself, you use baby wipes (seriously.) Second, to my knowledge, a military chaplain may not proselite while on duty. Third, given how dirty the soldiers get, the water in question would be filthy after the first baptism. (Not "pure" and "clean.") Fourth, 500 gallons makes for a very large baptismal pool. At best, I suspect it was a joke that got out of hand. I'll wager that the soldiers came across a pool of water. One stopped a soldier from going in claiming he had to be baptized and it went from there. At worse, it's simply a prank. (And those that say it can't be an urban legend because it was in the Miami Herald, have a lot to learn about urban legends.) Snopes doesn't have anything on it but likely will soon. (I can't prove a negative, so show me pictures and the court martial records for Josh Llano and I'll believe.)