The smell of stale and stagnant bong water is the last thing you want to smell while you're in a smoke session. This smell lingers even after you clean your bong without using the right products and ingredients. To get rid of this nasty odor, fill your bong with lukewarm water. Then, follow it up with one (1) to two (2) tablespoons of vinegar. Shake it and soak it for about an hour.