Water

Water was a prized liquid for those who lived under the surface on Ravolox. (DW: The Mysterious Planet)

Water was a seen as a source of great wealth for the Martians, On Mars, great warriors were often entombed in blocks of ice. (NA: The Dying Days, BFA: Red Dawn)

On some planets, such as Kar-Charrat, water was a form of sentient life in itself (BFA: The Genocide Machine, DWAN: Pitter-Patter)

Effect on species
A Thermortian Sand Worm's organs would collapse to sludge if it consumed water. (IDW: The Forgotten)