Purity: Wudu with Impure or Mixed Water
Practical Laws of Islam as per the teachings of Ayatullah Sistani
Ruling 264:
Wuḍūʾ performed with impure or mixed water is invalid, even if one did not know at the time that it was impure or mixed, or he had forgotten about it; and if one has performed prayers with that wuḍūʾ, he must perform them again with a valid wuḍūʾ.
-Ayatullah Sistani, Practical Laws of Islam, Purification (Taharah)