Zamzam water is the best, freshest, most beneficial, most beloved and most precious water there is.
Further, Zamzam water was dug up by Jibril and the source that Prophet Isma’il , drank from.
In the Sahihain it is narrated that the Prophet صلی اللہ علیہ وسلم said to Abu Tharr, who remained at the makkah for forty days without food (or drink) living on Zamzam water: It is a nutritious food.”
Muslim added that the Prophet صلی اللہ علیہ وسلم said: “And a cure from ailment.”
Furthermore,Ibn Majah narrated that Jabir bin Abdullah related from the Prophet صلی اللہ علیہ وسلم that he said: “Zamzam water is for whatever was intended behind drinking it.” We were told that Abdullah bin AI-Mubarak once said, “O Allah! Ibn AI-Mu’ammil told us that Muhammad bin AI-Munkadir related from Jabir that your Prophet صلی اللہ علیہ وسلم said: The water of Zamzam is for the purpose it is drank for, and I drink it to relieve my thirst on the Day of Resurrection.” This Hadith is of the Hasan (Sound) type.
Ibni Jawzi narrates the following statement
Many other people and I have tried drinking from Zamzam water for the purpose of being cured from various illnesses, and by the will of Allah, I was indeed cured from several illnesses. I In addition saw some people who lived on Zamzam water for a long time, fifteen days or a little longer without complaining from hunger. Such people would perform Jawaf with other people at a normal pace. Someone even told me that Zamzam water was his only food and drink for forty days and that he still had enough strength to have sex with his wife, fast and perform Jawaf many times. (Tibb an nabwi)