I have always wondered where do window cleaners get their water from? what if they are doing the windows of say a huge office, surely they can't just use one bucket of water?
If they think they're being watched they'll knock on someone's door and ask for a fresh bucket of water. I suppose with blocks, they are meant to just keep going up and down replacing the water.
Sorry to be jaded in my first sentence, but I can only go on the experience of my window cleaner!