I bought a Blue Devil water hardness test kit off Amazon to test the hardness of my water for about 10 dollars. The kit is a "titration drops" style kit.
It looks like this:
It comes with a plastic case, 2 bottles of "titration fluids", a clear plastic bottle, and a direction sheet.
This is how you test with it:
1. Rinse the vial out with the water to be tested multiple times. Then fill the vial to line "A" with water to be tested:
2. Add 2 drops of Hardness Solution "A" and swirl around vial. A violet color will develop if any hardness is present:
The violet solution:
3. Add Hardness Solution "B" in drops. Swirl between drops and count wash drop until solution changes to blue.
Adding Solution "B":
4. Calculation: Once water turns blue, multiply the number of drops of "B" it took to make it turn blue by 50 to determine ppm (of calcium carbonate) of hardness.
Example; 4 drops of "B" x 50 = 200ppm Hardness.
My hose water took 4 drops to turn the solution blue
So, my water would be 200ppm of Hardness. This can be converted to grains per gallon (gpg) by dividing this number (200) by 17.12. This would equal 11.7 gpg. This is hard water. Also ppm is equal to milligrams per liter (mg/L). So, 200ppm is the same as 200mg/L.
Here is a chart that shows what is considered hard and soft water:
180 very hard
So, my water is "very hard" this would explain the water spots I get no mater how hard I try to keep the car wet while washing and quickly dry.
The solution? There seems to be two:
1. A Water Softner for a hose. This is the cheaper option (around a hundred dollars). However, this will only "soften" the water, which means it replaces calcium carbonate (which is the culprit in most difficult water stains) and some magnesium with sodium chloride (NaCl). This won't leave a "spot free" finish, but supposedly, spots created by NaCl are much easier to remove and less frequent. The cartridges for this system can be "recharged" with salt which is very cheap.
2. Get a "RO" (reverse osmosis" de-ionizer. This is like the CR Spotless. However this is more costly (up to $450.00) and the replacement cartridges are not cheap either. However, this should create a true spot free no ion water that almost doesn't require drying ( theoretically).