Probably not super relevant, but lithium can interact dangerously with other psychoactive substances, particularly lysergamides. Would suck to end up hospitalized behind you had a glass of tap water during a trip.
Of course the number of psychedelic users probably isn't enough to care, I wonder if there are other, perhaps prescription drugs that could interact poorly with lithium.
If lithium is dangerous in those amounts, we should be removing it from tap water. Given that every study shows public health benefits (significant) and that it can vary 10x naturally occuring between high and low content areas, either what you're saying in those doses is false or we should be removing it.
Of course the number of psychedelic users probably isn't enough to care, I wonder if there are other, perhaps prescription drugs that could interact poorly with lithium.