I had a water butt installed recently (hosepipe ban, drought order etc. etc.) & have just washed the car for the first time using rainwater from the butt. Although it has a slight greenish tinge to it, it's fantastic for cleaning the car. Already warmed by the sunshine, it is much less streaky than tap water & seems to take longer to dry, so even on a hot day, I have time to finish washing all of it without having to worry about dry streaks on the bit I washed first. It also leather dry very easily. From now on, I will always use rainwater until such time as the hosepipe ban is lifted, and I can go back to using the Flash cleaner.