Short answer
There is no fixed amount: what matters is that water flows over every part. The sunnah is to be sparing. The Prophet ﷺ made wudu with about one mudd (two cupped handfuls) and ghusl with about one sa' (four mudds). Wasting water is makruh even at a flowing river. The four schools agree.
No set amount is fard. Washing means water flows over the part, at least a drop or two running off; just wiping with wet hands is not washing. Using more water than needed is makruh.
The four schools agree on this.
Explanation
Anas reported that the Prophet ﷺ made wudu (ablution) with a mudd and did ghusl with a sa' up to five mudds. A mudd is the amount that fills two cupped hands of an average man, and a sa' is four mudds. Scholars give different modern estimates for these measures, but either way they are far less than most of us use with a running tap or shower.
The four schools agree that this is the sunnah and not a fixed limit. Your wudu is valid with more or less water, as long as water flows over every part. Using too little so that parts are only dampened is not enough, and using far more than needed is disliked.
Practical tips:
- Turn the tap down to a thin stream, or turn it off while you wipe your head and ears.
- Use a jug or cup for wudu at home; it helps you see how little you need.
- In ghusl, wet the body first, then pour or run water once over everything, making sure it reaches the roots of the hair, the navel and the folds of skin.
- Washing three times is sunnah; more than three, without a reason, goes beyond the sunnah.
If you have waswasa and keep using more water to feel sure, that is a sign to stop: see waswasa in purity. Full methods: wudu and ghusl.
The evidence
Quran, Surah Al-A'raaf 7:31
۞ يَٰبَنِىٓ ءَادَمَ خُذُوا۟ زِينَتَكُمْ عِندَ كُلِّ مَسْجِدٍۢ وَكُلُوا۟ وَٱشْرَبُوا۟ وَلَا تُسْرِفُوٓا۟ ۚ إِنَّهُۥ لَا يُحِبُّ ٱلْمُسْرِفِينَ ﴿٣١﴾
O children of Adam, take your adornment at every masjid, and eat and drink, but be not excessive. Indeed, He likes not those who commit excess.
The general command against excess, which scholars apply to water in purification.
Sahih al-Bukhari 201
Sahih... يغتسل بالصاع الى خمسة امداد ويتوضا بالمد ...
"He would do ghusl with a sa' up to five mudds, and make wudu with a mudd."
The sunnah amount of water for wudu and ghusl.
Where the ruling is recorded
- Nur al-Idah with Maraqi al-Falah, Chapter on what is disliked in wudu. Wasting water is disliked.
- Radd al-Muhtar (Ibn Abidin), Kitab al-Taharah, sunnahs of ghusl. The mudd and sa' are not a fixed requirement.
This answer is pending review by the scholars on our team. 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.