Which film concerns an extraterrestrial searching for water to save his planet?

I saw the movie, thout David Bowie did well in the part, and thought it was one of the saddest films I've seen because he (the alien) was not able to return to his planet where the inhabitants were dying due to lack of water.

Daybonn, A classic cult fil

A very slow moving, boring movie. Kind of weird, too, and sad.