In a medium bowl, cream together the butter, brown sugar and white sugar. Beat in the eggs one at a time, then stir in the peanut butter, water and vanilla. Combine the flour and baking soda, stir into the creamed mixture. Finally, stir in the rolled oats and chocolate chips. Drop by teaspoonfuls onto an unprepared cookie sheet.
Bake for 8 to 10 minutes in the preheated oven, until the cookies are lightly toasted on the edges. Remove from the baking sheet to cool on wire racks.