How to remove hard water from windshield?

...keep trying with vinegar maybe soak rag and lay it on there to give it time to react. But possibly there is permanent damage to window.

 

A housemate long long ago had success removing hard water spots with jewelers rouge. But he didn't mention wiper scratches. I've never used it, so don't know the caveats.

 

I don't know if this would do what you want, but I have successfully cleaned lime and chlorine stains off of glass using "Lime Away". I am not saying it will remove the lines you are talking about, but it won't hurt to try it. I would not recommend spilling the product on your paint, as it might damage the paint.

Ron

 

when all else fails, focus on hypermiling.

 

This product is also known as "CLR", and it removes calcium, not chlorine... do be careful around your paint, and your skin for that matter.