It is narrated from Sayyidah Umm Salamah (may Allah be pleased with her) that she said: A single vessel, about half a faraq (a measure), would be placed for the Messenger of Allah (peace and blessings be upon him). He (peace and blessings be upon him) would begin with it (first), and then he (peace and blessings be upon him) and I would both bathe from it together.
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 19942