As a Manifestation, yes, but not manipulation. It's a desert world and I cannot allow the manipulation of existing water or you character could single handedly kill everybody with a flick of his wrist. Those who manifestor their powers will be unable to function with their continual usage against those who manipulate, as manipulation puts a lesser amount of strain on the host. Just so you are aware.

Also in the rules, and key points there are two defining ones which cover the constraints you said:

And Immortal may never manipulate something directly inside anything organic being. (I should edit that to include manifest)

And The Immortal versus Immortal rule, basically stating that their powers are weaker, or lesser, against one another as opposed to a standard civilian/creature.

Post that CS in the new OOC and I will get around to it tonight, or tomorrow.