Not being a jerk, but that simply isn't a valid statement. Neither you (nor your animals) need vitamins, calcium, phosphorus, etc, etc, in your water if you (or your animals) are eating a balanced diet. Ammonia will not be detectable in any municipal tap water, nor will mercury. You can drink pure water or tap, and the traces of things that can only be measured in parts per million or usually BILLION (in tap), or lack of iron, calcium etc in purified will make no difference whatsoever. This has been tested in peer review studies a zillion times. I care very much for my own life, as well as the animals I keep, and outside of reef aquariums, use tap water, personally.