There is a very simple fix. It is called a vinegar bath. Wash the vehicle as you would normally. Fill a spray bottle with 50/50 mix of distilled white vinegar. Spray one panel at a time and work it in with a microfiber applicator. Let it sit for a few seconds rinse and check. Repeat if necessary. This will safely remove all the calcium and other mineral deposits. Make sure to rewax when you are done.
If you have any other questions don't hesitate to ask.
Brett @ OCD