I currently use a water deionizer from On the Go. The units are available as a single tank model which has the two different media mixed in a single tank and I have a dual tank model that has each of the two media required to deionize the water in seperate tanks. Processing the water through seperate media increases the efficiency of the process. (For reference, my Total Disolved Solids( this is what makes water spots) at home was 270 ppm and after treatment it was 3ppm.) The dual tank, mixed media unit will produce about 2 1/2 times as much deionized water as the single tank unit per media refill so over time is a better deal. These kits are not cheap, but you can wash the car and walk away...no drying, no spots what so ever! I let my Crossifre drip dry, and it looks better than me drying it with a towel or shami.