Drinking bong water will NOT get you high, but it’ll probably make you feel ill.
Ah the old urban legend that drinking bong water will get you high. You will not get high because THC, the psychoactive compound in cannabis, is not water soluble.
What you are likely to get from drinking bong water is sick with vomiting and/or a stomachache.
One resourceful fellow posted that you could use rubbing alcohol to squeeze out that last bit of THC not used in the bong rip to scrape some out kief. Personally I’m not that hard up for cannabis to extract it from my dirty bong and I get plenty of kief with 100x less effort from my grinder but to each their own!
However, it is a good idea on a regular basis to use that rubbing alcohol to clean your bong to avoid bacteria and germs from thriving. If you’re hard up for kief or just curious for a science experiment, you could try out that guy’s above advice and evaporate the used rubbing alcohol in a dish and scrape away afterwards!