I am currently on a 'Town' warte system .
I have noticed a significant debris residue under my dish drying rack, as I only hand wash my dishes.
The other day, while in a local store I noticed a man who was purchasing spring water by the 24 pack,
and I began to think back to the residue in my drying rack and thinking it may be high in mineral content and perhaps other debris.
Now I am beginning to rethink my water supply since I now question the quality of the local water supply, especially after all the recent rain.
Look up your local town/city annual water report. It will show you useful stuff.
Calcium and magnesium are good.