All perfect praise be to Allaah, the Lord of the worlds. I testify that there is none worthy of worship except Allaah and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
Flowing water that is mixed with impure water is considered impure. Impurity of that water is certain because it is stagnant water that is mixed with impurity and they can not be separated. Therefore, it is obligatory to avoid it. When that water touches either one’s garment or body, the affected part must be washed. Allaah Almighty says (what means): {And your clothing purify.} [Quran 74: 4]
Allaah Knows best.