They have been adding floride to the tap water for 40 years, which means all of us drank it and were fine. It's good for preventing cavities (not really a concern for a newborn!). There has been some recent controversy about whether the levels are too high, but as far as I know the side effect of that is just causing some brownish discoloration of the teeth if the levels are super high. Also not the biggest issue for a newborn. I wouldn't worry.