Is there a way to get the baseplayer on 

void OnItemUse(Item item, int amountToUse)
{
    Puts("OnItemUse works!");
}​

item.parent.playerOwner

It will return null if the item was not used by a player, so check for that.  (Such as fuel used from a BaseOven.)

im trying to detect on a water bottle when player drinks with no luck.. any other way to do this.

Merged post

i can get it to detect the watter bottle but it does not return the owner but other food items do.