Sayyiduna Abu Umamah (may Allah be pleased with him) says that the Messenger of Allah (peace and blessings be upon him) said: "Water does not become impure unless its smell and taste change."
The hadith is not strong; however, we know of no disagreement that water becomes impure when it is changed by impurity. And Allah knows best.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 1229