Their is a lot of disolved minerals in my local water. What is the most effective way to lessen or eliminate water spotting?
Are they still selling the Mr. Clean no-dry car wash system? Apparently it was very good at eliminating spotting.
I second the Mr. Clean Auto Dry system. I’ve got hard water, and therefore water spots, but the Auto Dry system leaves nothing but clean, no water spots at all. I think it costs under $30.
Or you can finish washing your car and then towel it dry.
The silicon blade (California Dry Blade) works really well. It’s kind of a hi-tech squeegee.
When I go to the car wash I use the spot free setting to rinse it off. It helps. The wax setting helps too.
I second that . . . get two nice bath towels and dry it off after you wash it. I usually dry my car after every wash, don’t forget the door jams and trunk jams . . . the area where things come together is a good place for water to collect and rust to begin. Rocketman
I’ll second that expect I use the siliconE blade, it’s a bit softer 
After the blade, you can use a hand towel to dry off what’s left. And it’s FAST.
I take mine for a short highway drive. If the water drops blow off they take the minerals with them.
The auto drying rinse systems like “Mr. Clean” add a surfactant to the rinse water tha breaks up the surface tension and allows the water to slide off in sheets. I’ve never tried one, but I hear they work.