Data point: I was exposed to fluoridated water for 30 years growing up. When I moved to a non-fluoridated community 30 years ago, my thyroid went haywire (fluoride competes with iodine for thyroid receptors so the thyroid suppression that I had adapted to was suddenly removed, a similar effect has been seen on fluoride exposed fetuses). Instant medical cash-cow. Two years ago I installed a reverse osmosis water filter so the less bioactive calcium fluoride was also removed from my diet. Since I added 360mcg of vit K2 to the 10Kiu of D3 and the magnesium citrate and the herbal thyroid concoction I’d already been taking every day, I’ve slept better, dreamed more and my thyroid symptoms have lessened.
Btw: our steam-engine medical establishment only recently came to appreciate the importance of our internal ecosystem (gut flora) in maintaining health. Water chlorination kills bacteria, It’s like drinking a little antibiotic every day. My pet theory is that humans evolved to drink surface (highly oxygenated) water, which would support aerobic gut bacteria, so I started ozonating my drinking water as well as drinking kombucha and other probiotic stuff. Mass water ozonation is a (more expensive) alternative to water chlorination fwiw. YMMV.