If you live in an area with hard tap water you're essentially drinking "mineral water" out of the tap.
Here's some data for ya:
Mineral Content of Tap Water in Major North American Cities: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1495189/table/t...
Mineral Content of Selected Commercially Available North American Bottled Waters: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1495189/table/t...
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.)