Chemicals in water - Bad?

[spindrift]

Does anyone want to take a guess at what, if any, detrimental effect there might be on the combustion chamber/cylinders from the long term use of water? There are dissolved chemicals and minerals in water that has not been distilled/de-mineralized. I'm most concerned about WMI in a towing situation where you're using a lot of water. I certainly am (30 oz./min.) because my truck doesn't have an IC.