Imam al-Shafi'i (may Allah have mercy on him) says: The narration that "when the taste, smell and colour of water change, it becomes impure" is reported through a chain that is not established according to the scholars of hadith. This is the view of the majority; I do not know of any disagreement among them.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 1230