I haven’t done extensive research on fluoride, but, I am aware that too much of it can cause adverse effects to the body. At the end of the day, the more we manipulate things away from their natural forms, the worse they turn out.

Perhaps purification plants could clean and remove the harmful substances from the water, then, add back a balanced formula or minerals and trace elements. I believe Nestle do this to their in their water production facilities.

The extra cost of the second step is probably not attractive to most companies though