[sjm]

It depends where you live I think. Your tap water, if it's good, should normally contain a lot of minerals already. If you're drinking some kind of reverse-osmosis filtered water, then what you're saying makes total sense.

I lived in Cambodia for a while, where tap-water is a no go for drinking, and even though we avoided buying plastic bottles (plastic is a huge problem particularly in S.E. Asia) and instead stuck to larger tanks of filtered water, we had to make a point of always having some bottled mineral water in the mix. It was quickly noticeable when you hadn't had enough (extremely tired, drowsy, etc.)