Is excess water after Netillath Yadayim usable for other purposes? For example, you wash for bread, and you leave water in the cup - can someone use that water, or do they need to empty and refill the cup? Another example, you wash for bread with a normal drinking glass instead of a designated washing cup - a little bit later, but soon enough that there's still some water left in the cup, you want a drink of water. Can you use the cup without pouring out whatever is left at the bottom, or should you pour it out (or even wash it out) before using it?
Taking a more serious case (at least as I understand the Shu"'A), what about after washing in the morning upon waking up?