Sayyidah Maymunah (may Allah be pleased with her) said: I took a ritual bath (ghusl) for major impurity (janabah), then the Messenger of Allah (peace and blessings be upon him) came and bathed with the water left over from me. I said: O Messenger of Allah! I have already bathed from it. He (peace and blessings be upon him) said: "Major impurity (janabah) does not affect water."
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 20407