The theory is that the heavier particles will stick to the water, and stay in the water, while the smoke will pass right through I believe. This isn't really all that true in practice as bongs don't filter out much carcinogens, and you'd have to show me a very convincing report that proves that warm water is a better filter than cold.

I really wanted to write because it gets you high, but I realized that wouldn't make much sense.
graph Reviewed by graph on . Cold Water Hot Water. Why do people say that cold water will cool the smoke but hot water will better filter it? What makes hot water a better filter? What makes water a filter anyway? Rating: 5