It is narrated from Hazrat Aisha (may Allah be pleased with her) that I and the Prophet (peace be upon him) used to perform ghusl of janabah from the same vessel of water; we would be in a state of janabah but the water would not become impure.
Hadith Referenceمسند احمد / مسند النساء / 24978
Hadith Gradingحکم دارالسلام:حديث صحيح، وهذا إسناد ضعيف لضعف جابر