I get a lot of questions about the water. First, we do not used reclaimed water, although it would be nice from an environmental perspective it is too costly and hard to keep clean and keep the odor down. So, all water being used is Chandler city tap water. Now, with that said we run all water used in the bays through an industrial water softener. The water on the spot free system is run through an additional industrial filtration system.
So, what does this mean for you? Well, particulate in the water is what causes water spots and we aim to reduce that to its lowest limits. When measuring particulate in the water with a TDS meter we get a reading on the number of particles per million. See wiki for a detailed explanation: https://en.wikipedia.org/wiki/TDS_meter. I find that the city tap water ranges from 450-650 any given week. The water out of our spot free system ranges from 7-15. The last bottled water I bought was around 100. So, using the spot free will definitely give you the best shot at no spots on your vehicles, but the only way to guarantee no spots is to use the spot free rinse and then towel down your car or let it dry before hitting these dusty AZ roads.