See if it leaves water spots or not. And there is no regulation for a state, it varies locally. I detail at my house usually, pretty soft water so I don't have to worry too much. I got a call one day to do a mobile detail less than a mile away from my house, it was the hardest water I have ever used, had bad spot after 10 minutes. Couldn't even dry the car without spots setting in.
I do feel a lot of weight in the water. I wash two black BMW yesterday, one with soap n one with onr, the onr was used with a BHB and came out great. The other with soap cuz it got some oil on the hood n windshield. I did the washes around evening so no water spots. as I was drying with crappy AG HD guzzler, I see remaining water that I had to use ONR for drying. But I need to know if my water is hard, so I'll head to target n grab the TDS
Water Supply Classifications (Water Quality Research Council) For those of you who are wondering how hard the water in your area is, here's a general map you can use - What Is My Water Hardness? - United States Water Hardness Map, What is my water hardness? • Soft Water- 0 to 1 grains per gallon • Slightly Hard Water- 1 to 3½ grains per gallon • Moderately Hard Water- 3½ to 7 grains per gallon • Hard Water - 7 to 10½ grains per gallon • Very Hard Water - over 10½ grains per gallon
