It is narrated from Hazrat Maymunah that once I was in a state of impurity, and ghusl was also obligatory on the Prophet (peace be upon him). I performed ghusl with water from a tub in which some water was left. When the Prophet (peace be upon him) came to perform ghusl, I said, "I have performed ghusl of janabah with this water." The Prophet (peace be upon him) said, "Janabah does not affect the water," and he performed ghusl with the same water.