Most mobile car washes and detailing companies prefer de-ionized water as their first choice for water filtration. They enjoy the spot free water and savings in time in the wash process. Although the cost is significant, it is nice to use, I must confess. Most all details or mobile car washes who use it do agree, it is a pleasure to work with, but there are less cost ways to filter water such as:
Reverse Osmosis (RO)
Rain Soft Filters
Soft -T Systems
Reverse osmosis is used in many manufacturing plants. Many times labs will use RO for testing. Many cleaners and manufacturers of circuit boards have RO facilities on their property. It is a great way to wash cars. No water spots. Like RO, de-ionized or distilled is also a great choice.
Usually, on-site dry cleaners make their own water. They usually choose distilled. Distilled water is a boiling process. The steam, when it cools is distilled. If you boil water on your stove, you will see condensation forming on the upper range (oven) when the condensation cools, it's distilled. Distilled water is also used in batteries. Since dry cleaners need the steam, this kills two birds with one stone. If you buy the local dry cleaners an extra tank to store unused steam, it will cool in the extra tank; usually over 100-gallons per day. Of course, you will in some way need to compensate them for this. Whatever deal you can make will probably be better than the de-ionized water costs.
De-ionized service companies such as Culligan along with Apollo Equipment Manufacturers have set up an entire industry to service new car lots and they make a lot of money doing it. They also service other industrial users such as manufacturers who put de-ionized tanks in line with RO systems to speed up the process and make ultra purified water.
If you are able to get distilled water at a location for trade remember to elevate the tank above the level of the tank on the truck. Gravity is the best way to transfer; ask god. Not to mention the fact that most good electric transfer pumps run between $ 240-600. This capital cost also affects your bottom line and a 200-gallon water storage tank is $ 400.
Magnetic scramblers are okay. It's a one-time purchase. You should expect to spend $ 150-300 for a unit, which is good for 50,000-100,000 gallons of water. If a water softener is put in line, then double that cost. Rain Soft Inc. makes an electric scrambler, which also has a salt container attached. In other words, it's a water softener-water scrambler all in one. It works especially well because it takes the scrambler and electrically charges it. Soft-T Systems are the best and cheapest pocket scramblers. They are two inches in diameter and ten inches in length. They fit anywhere. Very, very compact; only $ 100.
Water softeners remove the main culprits responsible fof the worst spotting from wash water but because it replaces them with another dissolved solid, soft water still leaves some spotting. For absolute spot free rinsing of course think; Reverse Osmosis (RO), De-Ionized (De-I) or Distilled. Think on this.