Many people use Garrett T turbos (T3's, T34's and T4's) very hard without water cooling, if you don't run water through it, always let it idle a little while before shutting off the engine.
I've not been using water through my T3, with NO problems.
Won't be running water through the T34 i'm putting on next week either (.48 about 350hp hopefully).
So the choice is yours, either way works.