Pure water is not good for you… You need your water to be contaminated with minerals at very least.

Also, our systems don’t like stuff to be too stesole as well, since that will make our defenses decrease over time. Being esposed to a reasonable level of bacteria and viruses is what male you stronger and build your defense.

I mean “reasonable” of course. And tap water is reasonable (at least, in developed countries so places like USA might not apply, right Flint?) clean to fit that description.

PS: there are stuff that will make you seriously sick in river and stream water, against which it’s pointless to build defences… So please don’t do that and always drink controlled water.

Fun fact, in the Alps every small village has a public fountain, where water is NOT controlled or checked, but still perfectly fine to drink specially of you have been drinking ot from young age, like I did. Others who grow up without drinking it, might feel some mild consequences if they drink too much.