It is narrated from Sayyiduna Ibn Abbas (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings be upon him) used to perform ablution with the leftover water of Sayyidah Maymunah (may Allah be pleased with her).
Hadith Referenceصحيح ابن خزيمه / جماع أبواب ذكر الماء الذي لا ينجس، والذي ينجس إذا خالطته نجاسة / 108