I have a 91 camaro that has water stains. Of course! It's BLACK!! So you can see them. I waxed it, and it helped a bit, but stains are still there. Any suggestions?

Wet sanding should take them out.

and then waxing again

wet sanding may not be necessary...start with compounding and polishing first. wax really won't help you as it is not meant to correct defects.
maybe tr sourcing a local pro who is good with paint correction.

I used denatured water and a microfiber towel. I don't know how you're going to get to them with wax over them but its worth a try.
I tried all kinds of things but none worked like the plain denatured water.
It was my moms idea and as crazy as I thought it was it worked on hard water spots that were left over from a wash that did not get dried properly.

One other thing Ive found since then is using this to dry after a wash.=

http://cloudfront.zoro.com/product/large/1ECE3_AS01.JPG

You can find it just about anywere and it stays damp in the plastic storage container so if I see any spots when I do my pre-drive walk around/inspection and dusting with the California Duster I just use it lightly over any spots and it removes them like magic.

I know a little something about how important regular paint maintenance is.
Heres my cars paint after 5 years of DD.

By the way this paint has never seen a product with wax in it.
Its all Synthetic polymers in a paste used just like wax except theres no buffing. Just wipe to on ,let dry and wipe it off.
Water beads and flows like its on glass.
Here it is = http://www.meguiars.com/en/automotiv...ate-wax-paste/

Im suprised no one has mentioned using a solution of vinegar and water.

Every couple months I run over the car with a soft foam pad on a low setting and use a very light polish. Then I'll seal it in with a nice synthetic wax. No problems, no fuss, easy maintenance.

makes friends with this....this machine is incredible.

http://www.adamspolishes.com/p-966-a...isher-kit.aspx

usae a vinegar spray to break down hard water and the wash with soap and water and wax

Give a clay bar a try. It works wonders for embedded dirt, bugs, tar, even overspray. Never wax over any deposits on paint since it is a sealer. Invest in a good chamois and wash in a shaded area so the water doesn't evaporate before you get a chance to dry it up.