I like elemental system but having to pause and fiddle with different (and limited) quantities of each element during combat is very clunky, it's like magicka but in crampt rooms against generic enemies.
The utility slot item being centered on your character also means that's it's only for heals and water, you could replace it with a medkit-type item and not have to pause the game to fill up your tank with heals every time you want to use it, or allow the player to aim it so it doubles as a grenade.
Needs work, but the concept is solid.