Hey Guys,
Just some food for thought:
The hard water (as has already been pointed out) is definitely causing the problem. A few things that you can do to minimize the water spots:
1). Wash the vehicle in the shade (direct sun evaporates the water leaving mineral deposits/water spots behind)
2). Dry the vehicle down immediately with a quality microfiber towel (Walmart has them in abundance)
3). Choose carwash soaps that tend to dry "spot-free" (
TurtleWax Zipwax carwash just to name one); they tend to have water softeners built in
4). When choosing a wax, avoid the carnuba waxes; they look great & I love 'em personally, but they encourage the rinse water to bead up; this, in turn, facilitates water spots. Use polymer waxes that cause a "sheeting action" with the rinsing water; this facilitates a spot-free finish
5). In the event that you already have water spots that you need to deal with use this product:
Meguiars Mirror Glaze 2 / Professional Fine-Cut Cleaner. It is safe & it is FABULOUS at removing water spots.

Just follow with a good grade of polish & wax.
6). In the event that you'd really like to get into this kinda stuff in a lot more detail (but still very easy reading), just go to this website:
http://www.properautocare.com/exteriorcare.html
Of course, the addition of water softening systems to your home/water supply helps even more, as it corrects the problem at the core. They can be rather expensive, though; I'm about to buy one of the portable units that I've seen advertised at Camping World
(
http://rvs.campingworld.com/browse/skus/index.cfm?skunum=6848&wListID=75751&src=WL)
Sorry about being so long-winded, but I used to suffer from awful water spots..............I have felt your pains.
This website will definitely help you get your trucks back to that showroom finish we all crave!
Regards,
Jerry