Bong water is composed of
only the crap from whatever you are smoking. Since smoking
water-soluble items through a bong would remove the drug before it got to your lungs, only non-water-soluble drugs are smoked in bongs. Marijuana is an example of this. There will be (almost) no
THC in the water, since THC requires temperatures over the boiling point of water to come out of the
pot.
In other words, anyone who drinks bong water, then says they are "really high" are probably the type who would say the same after taking asprin they thought was ecstasy.