I was reading some info on wikipedia about bongs and I came across this....
According to the study, water pipes filter-OUT the THC. I dunno about you but I've ALWAYS been told/heard that bongs, bubblers, and waterpipes all got you higher b/c the smoke went through the water first. Apparently this is not true. It's funny b/c my girlfriend always says she would rather smoke a blunt instead of the bong b/c it gets her higher and I always though she was crazy but not anymore, LOL.
I've seen several studies that have confirmed this. In all these studies though, joints preformed the best in the tar to THC ratio. Bongs still get me really high, but nowadays I've been using my Volcano.