Most smoking noobs fail to grasp how a waterfall should be used correctly so their knowledge on the subject ends here.
Because the hole is made in the side of the bottle not the bottom there is a certain amount of water that remains in the bottle this is not a design flaw. The idea is then to remove the head then place a finger over the hole in the side of the bottle and a thumb of the other hand over the top of the bottle. Then violently shake the bottle for a second or two. Because THC is not soluable in water only the impurities in the smoke will get absorbed into the water (nicoteen etc). Not only is the smoke cleaner but it is also much cooler so the user is less likley to have a coughing fit when trying to inhale the THC vapour.With a lot of the impurities removed the user recieves a much higher absorbtion of THC into their bloodstream than if they were to use the same amount in a normal pipe.
"cool lets make a bong dude"
"..Nice idea but i havent got anything to use as a down pipe"
"fuck it what about a bucket?"
"..nah they just choke me out.Its to much for me"
"hmmm....hey what about a waterfall?"
"woo hoo!... now your talking"