Hadith.17 - Abu Al-Hasan Imam Musa ibn Jafar Al-Kadhim عليه السلام was asked about the collected water in a public bath from people’s washings, which may get onto clothes.
Imam عليه السلام said: "There is no harm in it”.
There is also no harm in performing ablution with used water. When The Prophet صلى الله عليه وعلى آله وسلم performed ablution, people would take the leftover water from his ablution to perform their own. If a person performs ablution in a clean vessel, there is no harm in someone else using that water for ablution.
However, water used to wash clothes, to wash after major impurity (ghusl), or to remove impurities should not be used for ablution.
