Nice easy way...

Well heres a method i tested out the other day at home. Make a Blunt [if you dont know what that is, just look for it on google or whatever] now put the blunt near the bottom of the water bottle, Mark around that with a marker. Now take an Exacto knife, or scisors but they dont work as well. and cut out that. fill the water bottle up to about an inch or so before the Hole. light up ur blunt put it in tha hole and let it fill, the smoke will be soother for taking shots like that. Also Ice Cubes work really well too.
try this, its quiet fun.

ok....uhm....well this is really old and i've done this with a number of water bongs, bought ones work best you take the bowl out (you know the kind where you pull the bowl out when your ready to hit it, usually on glass water bongs) take the sweet put it in that and smoke it up, gets you super fucked