Short answer
The Prophet ﷺ called zamzam blessed and said it is food that nourishes. Abu Dharr lived on it alone for about a month. Muslims drink it for health, knowledge and any good need, with dua. It is ordinary water in its make-up, so store it cleanly; it has no religious expiry date.
Drinking zamzam is mustahabb, especially for the pilgrim, as is drinking plenty and making dua while drinking. Taking it home is allowed. Its blessing is established by authentic hadith; specific health claims beyond that are not.
The four schools agree on this.
Explanation
Zamzam began when Hajar ran between Safa and Marwah searching for water for the infant Ismail, and the angel struck the ground where the water burst out. The Prophet ﷺ said: "May Allah have mercy on the mother of Ismail; had she left zamzam alone, it would have been a flowing spring." When Abu Dharr told him he had lived on nothing but zamzam for thirty days and nights and gained weight, he said: "It is blessed. It is food that nourishes."
- Blessing: authentic and agreed upon.
- Nourishment: shown in Abu Dharr's case.
- Dua: a well-known hadith says "zamzam is for whatever it is drunk for". Scholars differ on its chain; many accept its meaning, and scholars have long drunk it with a specific need in mind. Ibn Abbas is reported to have asked for beneficial knowledge, wide provision and healing from every illness.
- Healing: Muslims drink it hoping for cure, which is fine as dua. Avoid repeating scientific claims or figures you cannot verify.
Does it expire? There is no religious expiry. Practically it is water: keep it sealed, clean and out of the heat, and do not drink it if it smells or looks off. Fake or refilled "zamzam" is sold, so buy from trusted sources. For how to drink it see how to drink zamzam, and for taking it home see selling and carrying zamzam.
The evidence
Quran, Surah Ibrahim 14:37
رَّبَّنَآ إِنِّىٓ أَسْكَنتُ مِن ذُرِّيَّتِى بِوَادٍ غَيْرِ ذِى زَرْعٍ عِندَ بَيْتِكَ ٱلْمُحَرَّمِ رَبَّنَا لِيُقِيمُوا۟ ٱلصَّلَوٰةَ فَٱجْعَلْ أَفْـِٔدَةًۭ مِّنَ ٱلنَّاسِ تَهْوِىٓ إِلَيْهِمْ وَٱرْزُقْهُم مِّنَ ٱلثَّمَرَٰتِ لَعَلَّهُمْ يَشْكُرُونَ ﴿٣٧﴾
Our Lord, I have settled some of my descendants in an uncultivated valley near Your sacred House, our Lord, that they may establish prayer. So make hearts among the people incline toward them and provide for them from the fruits that they might be grateful.
The barren valley where Allah provided zamzam.
Sahih Muslim 2473
Sahih... إنها مباركة إنها طعام طعم ...
"It is blessed; it is food that nourishes."
The blessing and nourishment of zamzam.
Sahih al-Bukhari 3364
Sahih... يرحم الله أم إسماعيل لو تركت زمزم ...
"May Allah have mercy on the mother of Ismail; had she left zamzam alone..."
The origin of zamzam with Hajar and Ismail.
Where the ruling is recorded
- Radd al-Muhtar (Ibn Abidin), Kitab al-Hajj. Drinking zamzam is recommended, with dua, and taking it home is allowed.
- al-Fatawa al-Hindiyya, Kitab al-Manasik. Drinking plenty of zamzam is recommended for the pilgrim.
Checked by our team. For a more accurate answer to your own situation, consult a scholar. Quran translation by Sahih International. Hadith Arabic from the standard editions of the six books and the Muwatta, with gradings as recorded there; the English is our own rendering. Spotted a mistake? Tell us.