water is fine. It lacks any nutrients and vitamins that may be in the water before it was filtered but they are in such small amounts it makes no difference. Besides, we get all the nutrients and vitamins we need from food anyway. Fluoride (for teeth) is added to tap water which the filter will remove. But as long as you brush your teeth daily, this isn't a problem.
I would venture a guess and say that RO
water is actually *better* for us than your average city tap water. There should be a minimum number of dissolved solids and chemicals in the filtered water that would make it healthier. Should also taste better as well.