From what I have read, the minerals in the water are a source of nutrition. I think the reverse osmosis filter removes all those mentioned, but not chlorine. Some of the minerals are absorbed through skin during showers as well, buy I haven't discovered any adverse effects from this, although the water treatment system salesman had quite a list. These were mostly skin issues such as dryness or rashes, none of which we have experienced. I'm not sure what the reverse osmosis system removed that is a trigger for my boys, but it was a noticeable difference - positive when we installed the system, and very negative very soon after it broke down.