Comment by fzeroracer

> Should we add that to everyone's drinking water?

Consider the following: Many water sources have a ton of salts and such in them naturally. Fluoride being one of them. The reason why water fluoridation became a thing in the first place is because it was noticed that higher natural levels of fluoridation resulted in fewer caries.

Water treatment in order to make it safe to drink often involves processes that remove and filter out these minerals and chemicals. Which means said things need to be added back in, as part of the treatment process.