how do u fill it I am doing tough mudder how would u refill it , could u do it thru mouth piece , could I put a shirt over that?
CHARLES M It has a cap on the bladder. you turn it and it opens.
ARNOLDO R The water pack is removable and has a spin off top to fill with water
ROGER B It works the same way all camel backs work. It has a water bag with a large opening in the back. This is unscrewed, and it is filled from there. I dont think you could fill it during a race. But with 70 oz, that should be enuff to get you through an entire mudder. I wear a shirt over the system, but i dont cover the mounth piece. I would guess your concerned about getting it dirty, but unfortunately i use mine for bikes, and dont have the mud issue you will face. I suspect your going to have to eat a little mud, if you want to drink during the race, that or come up with some kind of sock to cover the mouth piece
GREG H I usually wear a jersey over since it is pretty sheer. It can only be refilled through the main port but it has to be removed to do so. Unless it is a long event, 70 ounces should be fine.