Good grief, seems like something like this can only happen to me... though I've heard of it happening before... but here's the situation, where I park at the apartment the sprinklers go off near the truck each night. Typically I can get these off fairly quickly before the spots set in but for some reason it took me a few days this time, possibly a week... so I figured I'd just wash em off on my lunch break, no biggie... well I was washing and washing and guess what, some didn't wash off completely. When I felt the surface of hte paint, I can actually feel slight ridges in the clearcoat where many of the bigger water spots were.
I need to find a new parking spot where psrinklers are nowhere nearby, and guess I need to be a bit more vigilant in washing the water spots off when it rains, to prevent this problem from getting worse.

My kingdom for a garage with a 9'+ door.

 

Where they bumps? Could just be mineral desposits from the water. You may need to buff 'em out and get some serious wax applied to your truck asap!

 

they weren't bumps, they were actually divets in the paint... like imagine if you put acid on paint or something and it burned off hte first layer or two... so you could still see what paint color it was and everything, but you could also see that it was now missing some paint. Kind of hard to describe.

 

Sounds like a job for a digital camera! Next time capture some water from the sprinklers, send it off to a lab and see what's in it. Then make 'em pay for the repairs! I just can't imagine what the heck is in the water to do such a thing!

 

I agree, pretty weird... I'm working with one of my sponsors to see if they can get me a car cover that works with my "mods", in the meantime, I'll be parking about 1/4 mile away, where the sprinklers can't get me!

 

Lots of sprinkler systems use reclaimed water. In short, it's filtered and slightly treated. I have a feeling what you're seeing is a result of etching and, unfortunately, it's nearly impossible to fix to the point of not noticing it...