Wudu

'ablution' [wuˈdˤuːʔ] ⓘ) is the Islamic procedure for cleansing parts of the body, a type of ritual purification, or ablution.

Activities that invalidate wudu include urination, defecation, flatulence, deep sleep, light bleeding (depending on madhhab), menstruation, postpartum status, and sexual intercourse.

But if you are ill, on a journey, or have relieved yourselves, or have been intimate with your wives and cannot find water, then purify yourselves with clean earth by wiping your faces and hands.

"[5:6][2] Wudu by itself is mustahabb, a recommended act (مستحب), but it becomes obligatory in special conditions such as prayer, reading the Quran, tawaf, etc.

[3] Wudu, in a hadith of Abu Hurairah discussing the Day of Resurrection, said that Muhammad, when asked if he would be able to recognize Muslims, said, "Yes, you would have a mark which other people will not have.

[10] Shi'a Muslims also believe the Qur'anic mandate for wuḍūʾ comes in the sixth ayat of al-Ma'idah.

when ye prepare for prayer, wash your faces, and your hands (and arms) to the elbows; Rub your heads (with water); and your feet to the ankles.

Theoretically, one can perform one wuḍūʾ for Salah and this wudu would be considered valid for the rest of the day, unless you nullify it by certain means.

[15] Muslims who are unable to perform the prevailing form of ablution due to skin disease, a disability, or a lack of clean water, etc.