WarmAndSCSI

Lots of conflicting information in this thread, so I'll summarize...

If they are light water spots from puddles and the like, they can be removed with a good wash and quick detail. Use a good quality, sudsy soap and a quality microfiber sponge, followed by a good quick detailer spray with a microfiber polishing cloth. That should get rid of those kind of spots.

For bad hard water spots (sprinklers) where the paint has not been exposed to the sun for too long - where the water spots are just stubborn, crusty surface deposits - use a mixture of distilled vinegar and water on a sponge, or straight distilled vinegar after quickly washing the car. Wash as normal after that. Clay-baring will also remove these kind of water spots, but really isn't necessary.

For really bad water spots where there are still halos left after trying a basic wash, it will take some serious effort. These kind of spots only form if you allow hard water spots to evaporate on your car in the hot sun, and then leave the car exposed to sunlight for an extended period of time with the hard water spots still present - the clearcoat becomes physically etched by the sun exposure/baking action. You'll need to do a proper wash, clay bar, and then follow up with a medium-cut or stronger compound applied by hand or DA polisher. You can try a test area with a lighter compound or a non-abrasive paint cleaner, but I can almost guarantee it will not take the water spot halos out.

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