How does one perform Wudu with the most essential elements when water is scarce in the desert?

The minimum sufficient for Wudu' is to limit oneself to the obligatory acts mentioned in the Noble Verse: washing the face, hands up to the elbows, wiping the head, and washing the feet up to the ankles. The sufficient amount of water for Wudu' or Ghusl (definition) is not quantified by a specific measure; indeed, consensus on this has been reported. What has been narrated about the Prophet (peace be upon him) performing Ghusl with a Sa' and Wudu' with a Mudd is to show the minimum recommended amount, not a binding limit. Whatever the person performing Wudu' uses to thoroughly wash, even if it is less, is sufficient, and if it is not enough, he should add more.