'Water' is difficult to translate because it is such an extremely basic concept and not included in known canon. The other geographical word to do with liquid water is okaaz 'sea'.

More general translations require creative compounding. One attempt is rathrii 'river-essence', although rii denotes 'character' or 'spirit'. For drops of water, luv 'teardrop' can be extended; 'rain' readily translates to luvselok.

Failing that, there is the non-canon lom. You can hardly be held at fault for using it.