Just because it smells nicer and we pretend water filtration helps, doesn't make it heathier. Hookah is often worse because a long Hookah session can have more nicotine than a pack of cigarettes.
Yeah, I got into a Wikipedia edit war about this. The WHO has some studies showing that an hour of hookah smoking puts about the same amount of tar in the lungs as 20 cigarettes. I think the theory was that the cooler smoke is better tolerated and smokers leave it in their lungs longer.
I eventually gave up maintaining the page, and the hookah vendors who were my rivals have completely remove the citation. Also, it was hard to find in the first place and I don’t have access to a college library anymore.