I don’t know what it is, but rain makes such a huge difference. Electrolites? All the trapped atmospheric pollution that’s actually GOOD for us? Who knows, LOL!
Rinse your hair with rainwater; you’ll feel the difference.
We have a nice, deep well, so along with the rain barrels, we have a good second source of superb water with no additives, save a little iron.
City Folk can always use City Water, but let it sit in containers for a day or so to percolate some of the cr@p out of it. Do that for houseplants too, and you won’t have any white ‘crust’ on the top of the dirt in your houseplants’ pots. (Calcium, usually.)
I just don’t like the idea of that little disk in the water meter spinning round and round, so I can pay for chlorinated water for my veg patch and pay again on the sewerage bill for water that was never handled by the treatment facility.