Housebreaking an iguana?

Well, I want to buy an ig, and I will give it a bath atleast once a week, but to pee and poop, I read somewhere put them in their water bowl. WHAT?!?! Don't they drink out of that. And isn't it too cold for them to get into. And if that is what they are supposed to do, how do you train them to naturally go there, because I would like to let him roam. THNX