In a medium bowl, cream the butter with the brown and white sugars. Stir in the vanilla, egg white and water. Sift together the flour, bicarb soda and salt; stir into the creamed mixture. Mix in the chocolate chips.
Drop dough by heaping spoonfuls onto ungreased baking trays. Bake for 8 to 10 minutes in the preheated oven. Allow biscuits to cool for 1 minute on baking trays before transferring to wire racks to cool completely.