Getting hard water stains off window

One of the best and safest cleaners for hard water spots is automatic dishwasher (liquid) soap. It's made to dissolve lime and other hard minerals. I use this on my shower stalls in the house about twice a year (we are on a well ... very hard lime water here). Put the liquid soap on a wet sponge and simply wipe. You'll need to repeat and keep it wet, so smaller sections at a time and it will come off and not damage paint for windows. Do not scrub your camper with a scrubbie or anything like that. It will take the paint off. But the automatic dishwasher soap will dissolve very gently. Try it on your glass first if you doubt. Then your painted surface after you've seen it work on the glass. On my shower stalls, I don't use scrubbies either, just a soft wash cloth soaked with the automatic dishwasher liquid.

I know for a fact rubbing compound works. Took the water stains out of my tinted windows on my chevy. Kind of scary to do but it works without scratching the glass. Just so long as it's glass and not some sort of plastic or plastic coated. Try on a small area first then go for it.

You could try something like Lime Away on a rag using the utmost caution. If it runs down the side the the camper, you could have a worse problem. To rinse, use a slightly wet towel and even have someone hold a dry towel directly below the window. Gotta be sure you don't let the Lime Away get on the finish. Hard water is the pits!

One place we lived, I set up the oscillating sprinkler and some folks walking by almost had a stroke because we had really nasty water with iron or something in it...I didn't know as we'd just moved there Within just a few minutes, I had a lovely orangy color stain on the siding of the house from the water . It finally faded, but think how healthy that was for folks that didn't have all the fancy water treatment stuff we had to install. UGH!

try hot vinegar full strength, use gloves.