Tayammum (Ablution with Clean Soil)

When a person is too sick to use water or none is around when it is time to pray, he or she can perform tayammum in place of wudu and ghusl.

The requirements are as follows:
Intending to perform tayammum to remove any impurity.
Striking the pure soil lightly with the palms of both hands and passing the palms over the face one time.
Striking the pure soil again with ones palms and rubbing the right and left arms alternately from the fingertips to the elbows.
Tayammum is nullified as soon as the cause for performing it is removed (i.e., the sick person recovers or pure water is found). If a person performs tayammum and then prays, he or she does not have to repeat the prayer (salat) if the conditions for it are removed before the time for that particular prayer ends.