> Nobody should be subjected to mandatory fluoride in their tap water.

Why? Just for the sake of freedom?

I think this raises an interesting question.

Suppose we have empirical irrefutable proof a practice is beneficial and doing so would not hinder anyone's lives whatsoever (as in, you don't have to change your lifestyle at all). Can this practice then be justified?

For example, suppose that fluoridating tap water (at least in the quantities present in most municipalities) was shown through many longitudinal studies to not have any adverse effects but was shown to have positive effects such as improved dental health. Would you support fluoridating water then?