We're in a very high water-table area. They dump gravel on our road 5-6 times a year, and mother-earth just eats it up. Then, there's that dust when they grade. I can leave, perfectly clean...4-500' later....looks like it's been sitting for 6 months. I have to wash the cars, every time I use them. We have well-water. We haven't hand washed a car here, in 25 years.