I say, and with God's success: All the water of the well should be drawn out if possible, or its quantity should be estimated by the words of two men who are knowledgeable about water if one cannot draw out all of it due to the abundance of water and its generation. It is not a condition for the body to be swollen in order to draw out the water; for it was narrated from Ata : "A black man fell into Zamzam and died, so Ibn al-Zubair ordered that the water of Zamzam be drawn out, and the water kept flowing. They looked and found a spring emerging from the direction of the Black Stone, so Ibn al-Zubair said: 'That is enough for you.'" This is explained in Sharh Ma'ani al-Athar 1: 17, and in Musannaf Ibn Abi Shaybah 1: 150. Ibn Daqiq said in Al-Imam: Its chain of narration is authentic, as mentioned in I'la al-Sunan 1: 264. And from Ibn Abbas : "A black man fell into Zamzam and died, so he sent down a man to bring him out, then said: 'Draw out the water that is in it.'" This is in Musannaf Ibn Abi Shaybah 1: 150. However, if a human being who is in a state of ritual impurity falls into the well and is brought out alive, (40 - 60) buckets should be drawn out as a recommendation. See: Hashiyat al-Tahawi p. 36-37, and God knows best.