Sayyidah Aishah (may Allah be pleased with her) said that the Messenger of Allah (peace and blessings be upon him) and I used to bathe from a single vessel, and it held about the amount of a faraq (the name of a vessel) of water.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 926