The Difference Between Pure Water and Purifying Water

Question:
He asks: What is the difference between pure water (tahir) and purifying water (tahur), and what is an example of that?

Answer:
Purifying water (tahur) is that which is pure in itself and purifies others. It is water that remains in its original state, whether from rain, rivers, or wells, and has not had its color, taste, or smell changed by impurity. If its color, taste, or smell is changed by impurity, it becomes impure (najis) and it is not permissible to use it. This is the purifying water (tahur). As for pure water (tahir), it is that which is pure in itself but does not purify others, such as water that has been used for ritual purity, or water in which something pure, such as herbs or other pure objects, has fallen. This removes its purifying quality, making it merely pure (tahir). Yes.