It’s a byproduct of aluminum mfg and fertilizer mfg. Get a good water filter. Birkeys are great. Get a filter for shower to remove chlorine. Bad stuff. Look on YouTube for fluoride deception/lies vids.
I put a whole house charcoal filter in and we only use RO water for cooking, drinking.
I need to get a Berkey. We get our water from the aquifer, but it’s full of heavy metals/iron along with city added fluoride.