In order for Ghusl to be valid, there are conditions that must be met, and if they are not met, then Ghusl is invalid. They are: (1) Intention (Niyyah) The Prophet said: Actions are but by intentions, and each person will have but that which he intended. (Bukhari and Muslim) So it is essential, when beginning to do Ghusl, to have the intention of removing impurity (Janaabah) by doing that Ghusl. One of our pious predecessor said: The purpose of intentions (Niyyah) is to distinguish acts of worship from ordinary actions, or to distinguish one act of worship from another.  (2) The water used for Ghusl must be pure (Taahir). (3) The water should reach the entire body, so there should be nothing on the body that can prevent the water from reaching the skin or hair, because Janaabah affects the entire body. (4) The fourth condition is a matter concerning which the Scholars differed, which is continuity between the parts of Ghusl and not allowing any lengthy interruption between them.