Hello, my name is Linda and when I was a kid people use to put salt rock around their hot water heaters. My husband does not believe me and so my question is:

Was salt rock used only for insulation purposes?
And why was that certain mineral used?
Did the salt itself play a role with the type of water you received?

Thank you for your time,
Linda

The only place salt is used is in a water softner to make a brine to wash deposits. You might post this question in the plumbing section for a better answer.