When you do wudhu, some water drips of your face (this is known as used water). If you make wudhu with used and fresh water, is your wudhu accepted for a little bit of used water and a lot of fresh. What is the percentage of fresh water for wudhu to be accepted
The rule is that where unused water is more and used water is less, it would be OK. However is used water is 50% or more, then Wudhu with it will not be allowed.