CNN The Situation Room February 7, 2014 22:28:00
That the odor threshold for this chemical is very low. what that means in general terms is where the cdc has deemed this chemical to be safe at a certain level, it has to go almost 1,000 times below that level in order for the smell not to be. this is also in addition to the case issue that is at hand. people have a natural instinct like all of us, our water is not supposed to smell. so when you feel and smell black licorice in the water, people feel that the chemical is still in it, although in minute amounts and that's the reason that people are having the h hesitant to drink the water again...
Source: archive.org