The base rock beneath Lake Erie is limestone...Calcium Carbonate. It is a mineral. Iron isn't an issue here. The calcium carbonate builds up in the pipes over time. We call it 'hard' water. That is an issue for older houses with steel valves.
Iron is an issue with the walls of my shower, I do not want a softener. There is some cheap shower cleaner from Meijers that does a decent cleaning job.
I installed a whole house filter because my car was dirtier after I washed than before. Then I installed an RO filter because the water from the first filter left a ring in my coffee mug.