Is the hand considered defiled if it is found to have only the transparent color of water on it, along with a doubt about the presence of impurity or its mixing with water that has retained its color, and is the hand purified by washing it once without distinguishing between the color of the impurity and the color of the water?

There may be an impurity that has no color, or is like water. The fundamental principle is to assume purity in anything whose impurity we doubt, so we do not pay attention to doubts until we reach absolute certainty of impurity. If something becomes impure, then the ritual impurity is removed merely by pouring water over it and increasing its quantity. We advise shunning and ignoring obsessive thoughts.