All life as we know it requires water. There are some forms of plants, animals and many microorganisms that can live for a long time, maybe decades, in completely dry conditions without water. An article by Peter Alpert in the Journal of Integrative and Comparative Biology discusses these. They can dry up and go completely dormant, but then years later become fully functioning when they get wet again.

Some scientists believe that other forms of life that are not based on water may exist in the universe. Perhaps they exist in an ammonia environment. However, nothing like this has ever been found. An article in Nature by Philip Ball discusses the various scientists looking for non-water forms of life.