it really depends on the material your house was made out of because i can pretty much smoke with my bedroom door open and my grandmas room is right next to mine and you cant even smell it unless youre actually in my room. but my friend goes through ever precaution and stills gets busted. i think it also might have something to do with the fact my grams smokes cigs in her room too but i mean a waterfall grav shouldnt smell that much at all unless you fuck up the hit or something.