I'm really at a loss here. I regularly clay, wash and wax my car. I use hardwax every few months and for every wash in between, I use some type of spray wax/quick detailer. My paint feels like glass. I don't get how the calcium in this water could penetrate the paint.
Past: 1999 Techno Violet Metallic M3
Present: 2011 135i 6MT