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.)
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...